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THOMAS CHARLES BRIDGES
(WRITING AS T.C. BRIDGES)

THE CITY OF NO ESCAPE

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Serialised in The Crusoe Mag., Dec 1924-May 1925

First book edition: George Newnes, London, 1925

This e-book edition: Roy Glashan's Library, 2018
Version Date: 2018-05-11
Produced by Keith Emmett and Roy Glashan

Only the original raw text of this book is in the public domain.
All content added by RGL is proprietary and protected by copyright.

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Ex Libris

Illustration

The Crusoe Mag., December 1924, with first part of "The City of No Escape"


Illustration

"The City of No Escape," George Newnes, London


Illustration

"The City of No Escape," Title Page


TABLE OF CONTENTS


Frontispiece.

Illustration

Nick, with the Robot clinging to his neck, was left dangling.


CHAPTER I

NICK PREST stopped, gazed at the left-hand cliff, went on a few paces and stopped again. "This is it," he whispered as he turned, and the other three crept after him, silent as ghosts.

The bottom of the gorge was filled with old lava, black and brittle as bottle glass, but the cliffs which went up endlessly on either side into the African night were of limestone. All was still as death. Not even a jackal cried beneath the stars.

A low arch gaped in the cliff face, and Nick passed in under it.

"Wait! No lights yet," came back his voice out of the velvet blackness. "Be careful. It's steep."

For a while there was no sound except the soft shuffling of Nick's feet as he moved slowly down a steep slope. The darkness was horribly daunting to the others, but Nick knew the way and they trusted him implicitly.

A beam of white light broke out from Nick's electric torch, and fell upon the rock floor of a wide passage which sloped steadily away into the bowels of the earth.

"All right so far," said Nick. "We are well below the level of the cave mouth. No light can show outside."

"You're sure scared of Bastin, Nick," remarked Mort Bradby, rather scornfully.

"I am," Nick answered curtly. "We've dodged the fellow so far, but if he had the least suspicion that we were here I wouldn't give two pins for our lives. What do you say, Jeremy?"

"I say you are right," said Jeremy Stretton, whose reddish hair and clear skin contrasted strongly with Nick's dark leanness.

"Yo' bet Marse Nick am right," added the last of the four, a little nigger, ugly as a monkey, but as strong and as active.

Mort shut up and they went on. It was easy going, for the floor was wide and level. No—not quite level, for the centre was slightly hollowed.

Jeremy noticed this and spoke to Nick. Nick nodded. "Feet, Jeremy. That hollow has been made by the tread of feet, and if I am not mistaken their owners were dust a few thousand years before we were born."

The passage sloped steadily, and soon its invaders were far below the level of the old lava floor which lay solid in the gorge outside.

Nick's torchlight flung out gleams of colour from the walls. Mort saw and stopped. "I say, look at those pictures," he exclaimed.

"Yes, there is the dog's head of Anup, and the beaked face of Thoth," said Nick. "By the look of it that blighter Bastin is on the track of something big."

"Can't we stop and look at them?" begged Mort. "Where there's paintings there's likely other things—things dad would be mighty pleased to have."

"We have no time," Nick answered. "Bastin and Kasim went much farther than this. What really matters must be a long way in, behind the big fall."

A mass of broken rock showed, blocking half the passage. Above was the break in the roof from which the stuff had fallen.

"Earthquake," commented Nick, in his brief way. "Probably the same time as the fissure eruption which flung out the lava and buried all Feshan."

Beyond was a second fall, but it was easily passed, and they had travelled nearly half a mile into the heart of the hillside before they reached a third fall larger than the other two. Part of the wall had broken away, leaving a deep hole in the left side of the gallery.

Nick stopped. "That's where I hid last night," he said. "The big fall is only about fifty yards farther on. It was that which stopped them."

"You looked at it?" asked Jeremy.

"Yes, after Bastin and Kasim had gone. It blocks the whole passage."

Mort cut in. "Where did they get the jade thing they showed to old Durham?"

"I can't say for certain. They may have found it in here, or likely as not Bastin brought it with him to humbug the Professor."

"But why would Bastin want to fool him like that?" demanded Mort.

"Because he's out for loot," replied Nick. "He means to go the whole hog. I heard enough last night to make me certain of that."

Mort stared. "I don't get you, Nick. Why should Bastin try monkey tricks? Dad promised to go equal shares with him on all finds, and he's paying ten thousand for showing us the way to Feshan."

"Ten thousand cuts no ice with Bastin, Mort. The man thinks in millions. He is on the track of something big. I don't know whether or not Kasim put him up to it, but I'm as sure of what I say as I am that this beast has simply been using us to get here."

Jeremy whistled softly. "You go the whole hog, old man," he remarked.

"Don't you believe me?" demanded Nick hotly.

Jeremy shrugged his great shoulders. "I dare say you're right. Myself, I can't stick Bastin at any price. I never could. And Kasim is a crook. You've only to see him once to swear to that."

Mort looked thoroughly unhappy.

"What are you going to do now?" he asked.

"Have a look at the big fall and see if it is possible to get by," Nick answered. "From what I overheard last night while I was shadowing those two blighters, the secret, whatever it is, lies beyond."

"You didn't gather what it was then?" asked Jeremy.

"No. Neither of them said much. But I'm certain it was something big, for they were so careful to keep it dark. You heard Bastin tell the Professor that the piece of jade came from a cave north of the Camp? And this is two miles in the opposite direction."

As Nick had said, the big fall completely blocked the passage, and the rocks of which it was composed were so huge that at first sight it seemed hopeless to dream of going farther.

Nick handed Jeremy the torch. "Keep it on me as I climb," he said, and started up the sloping face of the fall. A great rock loosened by his weight came thundering down, and the others had to jump for their lives.

"Look out, Nick!" cried Jeremy, in a scared voice.

"I am all right," came back Nick's voice; and, as the dust cleared, there he was at the top of the fall close against the roof of the gallery.

He struck a match and held it close to the roof. The others distinctly saw the little flame flicker.

Nick turned. "Air is coming through," he said. "I don't think there is much breadth of stuff between me and the other side. If you will come up, Jeremy, between us we might clear a way."

"How's the roof?" asked Jeremy.

"Solid as the floor, by the look of it. I don't think there is any risk of a fresh fall."

Jeremy handed the torch to Mort and climbed. The stones were more firmly locked than he had expected, and he reached Nick's side without disturbing any.

"Feel the draught?" asked Nick.

"I feel it all right," Jeremy told him, "but it's going to be a job to make a passage big enough for us to get through. At present there's no room for anything larger than a rat."

As Jeremy said, the prospects of getting past the fall seemed extremely slender, but Nick knew exactly what he was about. He had been trained as a mining engineer, and had had plenty of experience of underground work. He seemed to know exactly what stones could be moved without disturbing others. Each as he picked it out he handed to Jeremy, who, in turn, dropped it back down the slope behind him.

The heat was fearful, but luckily there was not much dust, and they got on faster than had at first seemed possible. Some of the smaller stones Nick lifted sideways, building them up against the roof. It was a dangerous job, but both the workers were too busy to give much thought to that.

All of a sudden there was a crackle and a roar. Nick fell forward, and Jeremy grabbed him just in time to save him from going headlong down the far slope.

"We've done it, Jeremy," said Nick. "We're through. Tell the others to come."

A minute later and they were all four on the level floor on the far side of the barrier.

"We're one up on Bastin," exclaimed Mort triumphantly.

Nick looked back. "Don't boast," he said warningly. "As it is I've half a mind to stop that hole before we go farther."

"You surely don't think the fellow will follow us?" said Mort. "And we haven't too much time," he added, glancing at his wrist watch. "It's past midnight."

"We'll chance it then," said Nick. "Come on. Hullo!" he exclaimed, "there's a rare echo. The roof must be higher."

As he spoke he raised his torch, and the white beam cutting the darkness showed that they had left the passage and were in a cavern of such dimensions that the electric ray was not strong enough to reach the far wall.

"Is this what Bastin was looking for?" Mort asked eagerly.

"That's what we have to find out," Nick told him. "Let us see what we can discover."

The cave itself was far too large to be artificial, yet the floor had evidently been levelled by the hand of man. So far as Nick's light went the place seemed to slope towards the centre like a monstrous saucer.

As they advanced, suddenly the lighted area gave way to an intense blackness.

"Looks like a hole," Nick murmured, and quickened his pace. Next moment all four pulled up short at the edge of a tremendous pit.

"It's suah some hole!" gasped Jake in an awed tone as he gazed down into the monstrous depths. He was right. The pit resembled a mine shaft, only that it was about twenty times the size of the biggest ever dug. It must have been fifty feet across with rock sides dropping sheer into absolute blackness.

Nick, who had nerves of cast steel, stood upon the extreme edge, pointing his light downwards. Then suddenly he grasped Jeremy by the arm. "Look!" he ordered. "Look, Jeremy. Do you see it? Don't be scared. I will hold you."

For a moment Jeremy's very brain reeled, but presently his senses steadied and he saw what Nick was pointing at.

"A ledge," he said. "A ledge sticking out from the side."

"A landing," corrected Nick with a little thrill in his voice. "And stairs. You see them?"

"Stairs," repeated Jeremy. "Yes, I see them."

They all saw them. Massive stone steps circling down into the depths until they passed clear beyond the uttermost ray of the torch.

"Thirty feet," said Nick, with his eyes fixed upon the platform. "Thirty feet—no more. Jake, give me the rope."

"You're going down?" asked Mort in a half-scared voice.

Nick did not even trouble to answer. He was uncoiling the length of strong Alpine rope which Jake had handed him.

"I got de bar, Marse Nick," said Jake, and took a short steel bar from the bundle he had been carrying on his back. "And heah's a mighty good place to fix it," he went on, pointing to a narrow crack in the rock close to the edge of the pit.

Nick nodded. "Yes, that is safer than letting you chaps hold it," he said, and with his quick, clever fingers he wedged the bar in the crack and fastened one end of the rope to it. He flung the loose end over and it fell exactly on the wide ledge below.

"You coining with me, Jeremy?" he asked.

"You bet I am," Jeremy answered. "Can't we all go?"

"No. One had better stay and watch the rope. You, Mort, you stay. Your head isn't as good as mine and Jeremy's."

Mort looked relieved. "I'll stay," he said, "but can't Jake stay with me?"

"Yes, you and Jake stay. You've got candles."

Jake was anything but pleased. He was as keen as Nick himself to see what was at the bottom of this amazing pit. But Nick was his boss, the person he admired more than anyone else on earth, and he did not say a word. Only his face showed what he was feeling.

Nick slipped over the edge and slid rapidly down the rope, and as soon as he was safe on the platform Jeremy followed. Then Nick started down the steps.

Not steps, for they were great shallow stairs, each nearly two feet in width and cut with amazing accuracy out of the solid rock. Though somewhat worn in the centre, they were sound and solid as the day on which they were made, heaven knows how many centuries ago, and down them Nick and Jeremy raced at top speed.

Ten times they swung round the great circle of the shaft and then they reached a second landing. Nick pointed his torch downwards over the unfenced edge of cut stone.

"No bottom yet, Jeremy," he said.

Jeremy looked upwards at the tiny circle of dim light which was all that could be seen of Mort's candle.

"And we are all of three hundred feet below the cave floor," he answered. "Nick, this thing is so big it begins to scare me."

"It is big," agreed Nick, "but, after all, we have coal pits a mile deep."

"But not with shafts like this. It doesn't seem credible that man could ever have made such a hole."

"He didn't," replied Nick curtly. "This is or was a natural shaft, but it has been enlarged and straightened out by men. Still, as you say, it must have taken a bit of doing. Are you coming on?"

Down they went, their footsteps sending ghostly echoes whispering up and down the tremendous stone funnel. And when they stepped again on the next landing the candle light above had dwindled to a mere dot. Yet still the great flight swung endlessly downwards into the unknown.

Jeremy looked grave. "Nick," he said. "It will take us the dickens of a time to get back, and I don't quite like leaving those two alone up there. Mort's none too steady. He might get the wind up and do something silly."

"Jake won't let him," Nick answered briefly. "Do you want to go up again?"

"Not I. I'm crazy to see what's at the bottom of this hole. If it's on the same scale as the way down, it ought to be something worth seeing."

"If we don't take our chance now, goodness knows when we shall get another," said Nick. "You can bet your boots that Bastin will be here to-morrow."

"All right. Let us go on," said Jeremy, but before either of them moved there came a sound from above, a terrified shout which boomed hollow as if through a giant speaking-tube: "Nick—Nick—where are you?"

"Told you so," said Jeremy. "Mort's scared."

"Young ass!" growled Nick. Then raising his voice: "It's all right. We're quite safe. Wait for us."

"Come back! Come back!" came the voice again, and now there was no doubt about it. Mort was horribly frightened.

Nick muttered something under his breath. "We shall have to go back, Jeremy," he said angrily. "All right, Mort," he shouted, "we are coming."

He and Jeremy started back, but going up was not so easy as coming down, and they were both panting when they reached the first landing. And, as they stopped to recover breath, a new sound reached their ears. Footsteps were coming racing down from above.

Nick stiffened. "Crumbs, Jeremy, the young fool has come down the rope!"

"Both of them," added Jeremy. "By George, Mort must have got a proper scare before he trusted himself over the edge. Yes, there they are—see their light. We may as well wait here for them."

The light came circling down the shaft, the footsteps rang closer and closer, and presently Mort, closely followed by Jake, arrived on the landing.

His face was white and streaming with perspiration and his eyes almost bulging from his head.

"What is the matter?" demanded Nick. "What crazy trick is this?"

"Crazy!" gasped Mort. "I am—nearly. Oh, if you'd seen them!"

"Seen what?"

"The ghosts. Two of the old Egyptians," said Mort, shivering.

Nick stared at him. "Ghosts," he repeated scornfully. "Did you go to sleep and dream them?"

"Dream!" cried Mort angrily. "They were ghosts, I tell you. Ask Jake. He saw them."

"Marse Mort am right," said Jake. The little negro's face had a nasty grey tinge and his eyes were goggling. "It's true, Marse Nick. Dey was 'hants,' and dey come up behind us quiet as death. We jest shinned down dat rope quick as light. We'd suah hab been dead if we hadn't."

Nick turned to Jeremy. "Some monkey business here," he said sternly. "We must go back at once and see what is up."

He started as he spoke. Jake caught hold of him. The little fellow was in an extremity of terror. "Do' ant yo' go, Marse Nick. Dey'll sure hab you if you goes up dar."

Nick was very angry, but he kept his temper. "We can't stay down here, Jake," he said quietly. "It is better to face ghosts than starvation. Don't be afraid. I will see that you come to no harm."

The words were hardly out of his mouth before from above came a laugh, a laugh so hollow, so cruel-sounding that it made even Nick shiver a little. Next moment something came whirling down past them and shot out of sight into the black abyss.

But not before both Nick and Jeremy had seen it.

"The rope!" gasped Jeremy. "That was our rope, Nick."

"I saw it," said Nick, and that was all.

For several seconds no one spoke. They stood gazing down into the blackness into which their one link with the upper world had vanished.

Nick broke the silence. "Bastin," he said briefly. "It can't be anyone else."

Mort looked at him with horrified eyes. "You mean that it was Bastin and Kasim dressed up as ghosts?"

"I have not a doubt of it," replied Nick.

"B—but what are we going to do now?" gasped Mort. "How can we get back?"

"We can't," said Nick quietly. "Not by the way we came, at any rate. Our only chance is to find some other way out."

Mort staggered and leaned against the wall. His face was like paper. "And it's my fault," he said hoarsely.

Nick laid a kindly hand on the boy's shoulder. "Buck up, Mort. We are not blaming you. I know that if you had not thought they were ghosts you would have kept your end up."

He turned to Jeremy. "We had better go on down, Jeremy. What do you think?"

"It is the only thing to do," agreed Jeremy. "How much water have we got, Nick?"

Nick shook his canteen. "Very little. We drank most of it after getting through that fall."

They compared notes, and found that between them they had less than a pint of water. Jeremy had a small packet of chocolate in his pocket, and that was the sum total of their provisions. One pistol and a box of fifty cartridges, a packet of candles, their clasp knives and matches—that was their entire outfit.

Nick turned. "I'll take the torch," he said. "Don't follow too closely, for it is quite on the cards that Bastin may drop rocks on us—if he can find them."

But no rocks fell, nor was there any further sign or sound from above as the four went circling downwards into the depths. The way seemed endless, and now there was no friendly gleam overhead to show how far they had come. The stairs were firm and solid as ever, and at regular intervals came the broad landings.

On one of these Nick stopped. "Jeremy," he said, "does anything strike you particularly?"

"Yes, that the air is quite fresh."

"Quite so, but there is something else. The temperature is not rising as it should. The rule is roughly one degree for each sixty feet. We are nearly a thousand feet below the cave floor and there is no increase in heat."

"What do you make of it?" asked Jeremy.

"Can't say, I'm sure. But I'll allow it beats me completely."

"How much farther do you reckon we have to go?" asked Mort.

"I know no more than you," Nick answered. "And there is not so much as a loose stone that we can drop."

"Heah's a bit ob rock, boss," said Jake, whose sharp eyes had spotted a small lump of stone half buried in the fine dust which lay thick on the landing.

Nick dropped it over, and all listened intently. But the seconds passed and there was no sound.

Mort shivered. "Say, I don't reckon there is any bottom," he said. "This hole goes plump down to the centre of the world."

"Then that's where we have to go," said Nick rather grimly. "Come on, all of you."

Their legs were aching with the endless steps, and the intensely dry air had made them all cruelly thirsty. But no one suggested a drink.

Another landing and still another. "We're all of a mile down," said Nick aside to Jeremy. "As I said before, this beats me." As he spoke he pointed his torch downwards, then stood staring fixedly.

"There's the bottom," he said.

The light fell upon a floor lying no more than fifty feet beneath them. It was perfectly smooth and greyish in colour. In the centre was a curious snake-shaped mark.

"W—what's that?" gasped Mort.

"Our rope," replied Nick. "It's buried in dust, and it was the dust which muffled the sound of that stone we dropped to find the depth."

Nick was right, for when they stepped off the last of the stone stairs they dropped ankle deep into dust fine as flour which rose in puffs under their feet.

"We'll get our rope, anyhow," said Nick, and as he walked across to where it lay something crackled under his feet.

"What is it?" asked Jeremy.

"Just bones," Nick answered briefly, as he stopped and picked up the rope. Jeremy, too, saw the bones, and one was a little human skull, no bigger than a baby's. But he did not say anything. It was no use scaring Mort and Jake. Yet the ugly thought came into his mind that there seemed every chance of their fate being the same as that of this poor forgotten mortal.

Nick flashed the torch, and the light showed one passage running out of the shaft. "Hobson's choice," he said. "Come on."

Like the upper passage, this one sloped downwards. Nick and Jeremy both noticed it, but said nothing. Mort was not so reticent. "I say, we're still going down," he exclaimed. "This ain't any way out."

"It's our only way," Nick answered in his curtest tone. Jeremy, knowing Nick as he did, realised how little hope was left in the other's heart, and his own spirits sank. The one thing that saved him from utter despair was the plain fact that this passage had at one time been used by multitudes of people. Yet that was so long ago that the hope it left him was a terribly slender one.

The air, though still fresh, was hot and parching, and by this time they were all abominably thirsty. At a depth like this they might have expected to find water, yet the walls and floor of the passage were dry as bone.

Nick's torch, the light of which had been growing weaker and weaker, was now giving out altogether, and he stopped to put in a fresh battery.

"Strike a match, someone," he asked as he switched off the torch.

As Jeremy fumbled in his pocket for a matchbox, Mort gave a sudden yell. "Light!" he shouted. "I can see light. Look!"

They all saw it. A faint, bluish glow far down the passage. It was hardly more than a firefly might have made, yet it was light.

Nick stared a moment. "But not daylight," Jeremy heard him say under his breath.

Mort and Jake, however, had no doubts on the subject, and almost before Nick had got his torch working again they were both running towards the distant gleam. "What did you mean, Nick?" asked Jeremy as they followed.

"Mean? Why it's not dawn yet, man," said Nick. "So how can that be daylight?" Then he started on so quickly that Jeremy had no breath for reply.

The patch of light grew larger as they raced down the tunnel, but it had a bluish tinge more resembling moon than sunlight. And against it was a fine, dark tracery lying across the end of the passage. Then through the silence came a sound, the most welcome of any sounds which could possibly have reached their ears. It was the rush and gurgle of running water.

They all heard it and fairly raced, but Mort had the start and kept it. Nick and Jeremy, close behind, heard him cry out gleefully: "Say, boys, it's sure a river;" then, before they could reach him, his shout changed to a scream and staggering backwards he fell into Jeremy's arms.

"The gate," said Mort thickly; "don't touch it." Then he collapsed completely, and Jeremy laid him on the floor.

"The gate," repeated Nick, as he stared at it doubtfully. "Metal," he added; "and—and, if it were possible, I'd say electrically charged."

Jeremy hardly heard. He was bending over Mort. "I must give him water, Nick," he said.

"Yes, give him some water," agreed Nick, who had taken an old silk handkerchief from his pocket and was wrapping it around his right hand.

Stepping forward he cautiously touched the gate. His hand jerked back and a look of absolute amazement crossed his face.

"What in the name of anything have we struck?" he said hoarsely. "The gate is charged with electricity."

Jeremy was dropping water down Mort's throat, and the youngster was quickly recovering. He rose slowly to his feet and came and stood beside Nick. The gate, or rather fence, was made of thin metal bars, silvery grey in colour, and fitted on either side into masonry built into the rock. It was set across the narrowest part of the passage, which ran on beyond the gate for about a score of paces.

All that was visible at the end of the passage were the tops of what looked like three large, yellowish umbrellas, and a jagged spike of rock. These showed up strongly in a soft opalescent light, the source of which was, however, invisible.

"I suppose I have got to believe you, Nick," said Jeremy. "But it's a bit staggering."

"You'll stagger all right if you put your bare hand on that," replied Nick grimly. "Still, it can't be very heavily charged, or it would have finished Mort."

"But electricity means men," said Jeremy. "What is it? Are these treasure seekers ahead of us, and have they taken this means to bar our way?"

"That, or—" Nick paused and passed his hand across his eyes. "I don't know," he said, "I don't know; but, by thunder, I mean to find out before I am much older."

"But unless they are good enough to switch off the current, I don't quite see how it is to be worked," Jeremy said.

Nick did not answer. He was on his knees, and with his handkerchief wrapped round the knife handle so as to insulate it, was scraping at the foot of the bars, and Jeremy saw with surprise that the rock seemed comparatively soft.

Presently Nick got up again. "I thought so," he said in a tone of deep relief. "Jake, the rope." Taking the rope, he looped it round, one of the lower bars. "Now then, tail on to it, Jeremy. You, too, Jake."

Mort clambered to his feet. "I'll help," he said, and though he was still white and shaky, he laid hold valiantly.

Jeremy was an exceptionally strong man, and Nick, much lighter, was no chicken. They dug in their heels and began to pull.

As the strain came, the metal barrier began to creak and dust rose from the points where it was set into the floor.

"Pull!" snapped Nick. "Pull! If we don't get through we're done."

The sweat streamed down their faces, the gate groaned like a thing in pain.

"She's a-coming," panted Jake, and the words had hardly left his mouth, when the whole thing gave way with a snap and a crackle, so suddenly that the entire team went flat on their backs.

"Good business!" cried Jeremy, as he scrambled to his feet, "but how came you to think it would yield, Nick?"

"It's old—old like everything else here. The earth current had rotted the metal where it touched the ground. Electrolysis. You know what I mean."

As he spoke he was examining the sockets into which the gate had been set, and the others saw a look of absolute amazement grow upon his face.

"This beats all!" he said. "There is no wire."

"You're not going to tell me it's charged by wireless," said Jeremy.

"I'm not going to tell you anything. I don't know myself. All I do know is that I am most infernally thirsty."

"There's water near," said Jeremy, as he went forward. "Let's hope it's drinkable."

All four reached the mouth of the tunnel together and one and all stopped short, gazing at what was surely the strangest scene on which mortal eyes had ever rested.

In front a great slope covered with vegetation fell away towards a good-sized river that ran swift and deep in a rocky channel. The rock and the water were natural enough, but beyond these there was not one single feature in the landscape which was like anything they had ever seen before.

Mort was the first to break the silence. "Mushrooms," he said hoarsely, and pointed to the things that had looked like umbrellas.

Mushrooms they were, or toadstools, but of a size unknown elsewhere, and there were thousands of all shapes and sizes and colours growing on either side of the river. Forests of them, some at least twenty feet high. There were also thickets of a sort of scrub with yellowish leaves, the branches of which were bearded with heavy grey moss.

Opposite them this amazing landscape stretched away for perhaps three miles, and was bounded by gigantic cliffs similar to those at the base of which they had emerged, but to the left and right no boundary at all could be seen. It all lay under the same strange opalescent light, and looking up they saw that the rays came from a number of immense pale, shining globes which hung like soap bubbles in the void above.

The warm air was utterly still, not a leaf moved or rustled, and in the uncanny silence the roar of the river was astonishingly loud.

After Mort's first exclamation it was at least a minute before anyone spoke or moved. Then Nick turned to Jeremy. "Do you mind pinching me hard?" he asked.

"I suppose you think you're dreaming, Nick?"

"I'm almost sure I am. This can't be real."

"It's real enough," replied Jeremy quietly. "It's a cave."

Nick seemed stunned. By nature and training he was hard and practical, and his mind was not fitted to grasp things that his brain could not understand. Jeremy, luckily for himself and for the rest, had more imagination.

"A cave," repeated Nick dully.

"Yes. Don't you remember what Professor Durham himself said? 'Our real knowledge of the earth's crust is small. What fissures, crevices, and caverns lie beneath us we know not at all."

"But this growing stuff," said Nick. "And these lights!"

"There is air, water, warmth. Why should there not be vegetation? As for the lights, they take a bit of explaining, but so did that gate. If you ask me, the cave is inhabited."

Nick made no reply. Keen-witted, hard-bitten as he was, he seemed dazed. Jeremy took command. "Water first," he said. "After that we can plan."

He started down the slope, and the others followed.

The slope was steep and stony, but the surface was earth, not rock. They threaded their way among the monstrous fungi, and clumps of moss-hung scrub. Suddenly little Jake shrieked and leaped sideways.

"What's the matter?" demanded Jeremy.

"Dat mushroom. It done tried to bite me," replied the black boy, terrified.

The fungus to which he pointed had curious fleshy tentacles hanging from its outer edge. As Jeremy went near these began to sway gropingly towards him. He leaped back. "Ugh!" he grunted, and picking up a big stone flung it with all his force at the base of the horrid thing. The whole growth crushed into ruin and lay with its long arms writhing feebly.

Keeping away as much as possible from the bushes, they gained the river, which ran swift and deep between banks of dark-coloured rock.

Mort tasted the water. "Say, it's real good," he exclaimed, and handed the cup to Jeremy. They all drank.

"That's fine," said Jeremy. "Now then, Nick, what next?"

Before Nick could answer there came a great voice shouting to them. The sound seemed to proceed from directly overhead, yet looking up they could see nothing. Nor could they understand the words.

The shout came again enormously loud and plain, yet curiously hollow-sounding.

"Crumbs! What was that?" cried Jeremy.

"Sounded like a mighty big warning," said Nick. "It's put the wind up me properly. Get back all of you. We had better hide."

They drew back quickly behind a pile of rocks and waited in breathless silence. A minute dragged by, then suddenly the stillness was broken by the quick splash of paddles, and round a bend in the river above, a boat shot into view. A long, narrow craft with a curious raised stern. It was made of the same grey metal as the gate.

Yet it was not the boat, odd as was its appearance, which made them stare at it wide-eyed, but its crew.

There were six men in the boat, and stranger beings Nick and the rest had never seen.

They were dwarfs, not more than four feet high, but thick-set and immensely powerful. Their heads were almost as round as cocoanuts and perfectly bald. The only hair on their faces was on their eyebrows and eyelashes, the latter set above eyes which were large and prominent like those of owls. Their noses were thick, with very wide nostrils, and their ears were enormous and oddly pointed. Their skins were the colour of yellow clay, and their only clothes waist-cloths of some dirty white stuff which hung to their knees.

"Guess they wouldn't win prizes at a beauty show," Mort murmured.

"Shut up!" hissed Nick. "They'll hear you."

"They've heard that voice anyhow," Jeremy whispered in Nick's ear. "They know there is something up."

Jeremy was right, for the owl-eyed men had stopped paddling and were closely examining the banks. One spoke in low, growling tones and the steersman swung the boat towards the bank.

Mort shrank back. "Do you reckon they've spotted us?" he whispered.

"Heard us, more likely," replied Jeremy in an equally low tone. "Watch their ears. They're waggling like a dog's."

Nick leaned across with his mouth close to Jeremy's ear. His dark face was alight with excitement. "If they land we must collar their boat. Fire your pistol over their heads and rush past them."

Jeremy nodded and whispered the order to Mort and Jake. They waited, still as mice.

The boat touched the bank, and all her crew except the steersman landed, and came prowling up the slope. Their bat-like ears were plucked forward, and they were sniffing the air like hunting dogs. They were a repulsive-looking lot.

"Now!" cried Nick, and leaped to his feet.

Jeremy banged off his pistol, and in the heavy air it roared like a small cannon. The five owl-eyed men stopped short in amazement; and in a flash Nick and his party were past them.

Nick reached the boat first. The steersman made a vicious swing at him with his metal paddle, but Nick was quicker than he. His fist caught the dwarf on the jaw and knocked him head over heels into the river.

The force of Nick's jump had driven the boat out into the stream, but Jeremy sprang in waist deep and grasped the stern.

"All aboard!" he roared, and the other two hurled themselves over the gunwale.

Jeremy scrambled after, and Nick, snatching a paddle, swung the boat head down-stream. "We can't go up," he said briefly. "Current too strong. Besides, that's the way from which the dwarfs came."

The boat was light and easily handled, the current strong, and with four paddles working they shot away at a tremendous rate.

"No more of the savages anyhow," said Jeremy as they drove round another curve. "But did you ever see such queer brutes, Nick? My word, they must have been down here about a million years to get those owl's eyes and bat's ears."

Nick shook his head. "Dry up!" he snapped. "It won't bear thinking about. I shall go looney if I once start trying to figure it out."

The banks grew higher, the stream narrowed and ran faster. They heard a dull roar ahead.

Mort grew pale again. "I say, that sounds like a waterfall," he said unhappily. "Hadn't we better land?"

"Where?" asked Jeremy as he looked at the cliff-like banks. Next moment the boat had swung round another curve and was dropping away beneath them on a long, straight slide. It was like a water-chute, only the bump at the bottom was worse. But the boat rode the wave like a bird and splashed into smoother water beyond.

The stream widened again and for two or three miles they travelled safely and easily. But the banks were still too high to see anything except the pale globes which shone high in the vast arch overhead.

Another sharp curve and suddenly there was no more current. They were floating placidly on the edge of a great lake. To their right ran out a monstrous lump of barren rock, but behind it the upper level of the giant cavern was aglow with light far stronger than anything they had yet seen in this underground country.

"Something afire?" said Mort doubtfully.

"It's too steady for that," Jeremy answered.

"Go slow," growled Nick. "We don't know what we may run our heads into, in this nightmare land."

They paddled quietly round the point, then from all four pairs of lips at once came long, whistling breaths of amazement. Four or five miles away rose the far shore of the lake, and on a great level space above it towered a monstrous pyramid which seemed to stand nearly half a mile in height. But instead of grim blocks of granite this was built of some material which glowed translucent with lights of every colour of the rainbow.

After a long time Jake spoke. "Marse Nick," he said, "do yo' reckon dat's Hebben?"

Nick leaned back and burst into laughter that was very nearly hysterical. And as he lay and laughed, suddenly out of the vault above boomed the same great voice of warning which they had heard before the dwarfs came upon them.

Nick's laughter stopped as if a tap had been turned off inside him. "Where are they?" he asked crisply.

Jeremy pointed to the left where from the mouth of a shadowed creek a fleet of boats similar to their own was shooting swiftly out towards them.

Nick took one look at them, then drove his paddle deep into the water.

"Paddle!" he snapped. "Paddle like the dickens. It's our only chance."

Jeremy glanced back over his shoulder, and saw the whole fleet in full pursuit. "A mighty slim chance," he muttered. "Thirty of them at least, and half a dozen men in each."

"Which way, Nick?" he asked aloud.

"The pyramid," jerked back Nick. "If we can reach it ahead of the blighters we may save our skins."

For a while they kept their distance, but very soon their pursuers began to creep up. Jeremy looked back again.

"Nick, we can't do it," he said. "It stands to reason that six men can drive a canoe faster than four, and we have all of two miles to go. I vote we stop before we're too done, and try to fight them off."

"Fight them off!" repeated Nick curtly. "Fat lot of good that will be. There must be nearly two hundred of 'em. They'll simply smother us."

"You forget my pistol. Besides they won't come all at once. Look, how they're strung out. It's the only thing to do, Nick."

Nick stopped paddling a moment. "You're right," he answered briefly. "But don't try shooting the men, Jeremy. Plug the canoes. Mort, you and Jake keep her going steadily."

With only three paddles working, the pace of the boat slackened, and the dwarfs came up fast. But by this time they were well strung out. Jeremy waited till the leading canoe was within easy range before he fired, and his bullet ploughed clear through the thin plates of metal of which the canoe was made and, coming out below the water line, tore a hole as big as a man's fist.

Up to this the dwarfs had not uttered a sound, but now the ugly little brutes screamed in terror, and turning their boat, paddled desperately towards the nearest behind them and scrambled frantically aboard it. Their weight brought it almost gunwale under and Jeremy, firing again, holed it.

It sank in ten seconds, leaving its double crew swimming like fish and shrieking like crazy things. "Say, what are the fellows so scared about?" demanded Mort. And the words were hardly out of his mouth before one of the swimmers gave a hideous shriek and vanished into the depths.

The water swirled; a huge ash-coloured back ridged with horny spines showed for an instant. Then a second and a third of the swimmers were plucked down.

"You know now," said Nick briefly, but Mort only gasped and went very white.

Nick spoke to Jeremy. "That's checked 'em. We might make another dash for it."

"Come on," said Jeremy, driving in his paddle.

With a sharp ripping sound something whistled overhead.

"Dey's got slings," exclaimed Jake, and as he spoke a stone struck the canoe with a sharp clang.

Nick shook his head.

"This is about the limit," he growled. "Keep shooting, Jeremy."

But the dwarfs had learned the range of Jeremy's pistol and kept off, raining in stones from a distance. Mort got a nasty smack in the back, and things began to look worse than ever. Then, just as if a switch had been turned off, all the great overhead lights went out, leaving the whole cave in velvet darkness, in which the only point of light was the great gleaming pyramid. Then that, too, faded and disappeared.

"Dere, I knowed it," said little Jake sorrowfully. "Dat spike-top town was a heap too pretty to be true."

"We're done for now," said Mort. "Those dwarf things can see in the dark, and that's more than we can."

As he spoke there came a blaze of light. A great ray like solid white fire stabbed the utter gloom, and just missing the boys' boat, struck down upon the savage pursuers.

The mere reflection of it dazzled the boys. As for the wretched dwarfs, they simply flung themselves down covering their eyes with their hands.

Nick shouted. "What a trick! Here's our chance. Paddle, you beggars. Paddle like sin."

He did not need to ask twice. The canoe fairly leaped under the urge of four pairs of arms, and soon left the blinded dwarfs far behind.

"Straight for the pyramid," panted Nick. "The light comes from the top. Gee, but they must have some power behind it."

They drove on right under the great beam, but as they neared the far shore where the pyramid stood, they were lost in darkness.

"Steady," ordered Nick. "We don't want to bat the boat on the rocks. There's things in this lake I'm not keen to interview too closely."

"There's a light," exclaimed Mort, "and coming right to us."

A tiny light was darting towards them from the pyramid shore, and as it came nearer they saw that it was in the bow of a very small but most exquisitely formed boat. What drove her they could not tell, but there was only one person in the boat, and that a girl.

"Jer-rusalem!" gasped Mort, and if the others did not say as much, they felt it. For the girl was just about as sweet and dainty a creature as any of them had ever set eyes on. She looked to be about fifteen, was tall and slim, with the clearest brown skin and great dark eyes.

"And I'll be sugared if she hasn't got her hair bobbed!" said Mort, in a hoarse whisper.

As the wee boat came closer, the girl stood up and beckoned to the boys, and called out something in a sweet, ringing tone.

"She's talking old Egyptian!" said Jeremy in a strangled voice. "'Water gate,' she said, I understood that much."

As he spoke the girl put over the tiller, her boat spun round and began to run back towards the shore.

"All together," roared Jeremy, and with all the power of his giant muscles, drove the canoe after their guide.

The little boat shot ahead, light as a swimming-bird, and the shore was already visible in the reflected glow of the super searchlight, when the girl gave a sharp cry of fear. At the same moment her boat rose as if it had struck a submerged rock, and instantly overturned.

"Another of those water fiends," gasped Nick, but the words were not out of his mouth before Jeremy, knife in hand, had leaped into the black depths.


CHAPTER II

JEREMY struck the water head first and vanished. For the moment all that was visible was the little boat upside down, yet still floating, and the girl clinging to it. But the light reflected downwards from the great white beam above was so faint that her small white face was a mere blur in the dimness.

"The pistol! The pistol, Jake!" cried Nick fiercely.

Then, as Jake fumbled in the bottom of the boat for the pistol which Jeremy had dropped before springing overboard, all in an instant the great searchlight was switched off, and the soft radiance of the overhead lights flung up the whole scene in strong relief.

The water clear as glass; Jeremy swimming like a seal, six feet below the surface; and, beyond, between him and the girl, a vast pale-coloured form with a long, narrow head, jaws like scissors, and eyes the size and shape of saucers.

The brute had seen Jeremy and apparently was hesitating which to attack first, him or the girl.

It hesitated a moment too long, for Jeremy reached it, and those in the boat saw his great right arm drive upwards and bury the knife blade in the belly of the monster.

With the sting of the steel in its entrails, the vast water beast went mad. It shot upwards, leaping like a hooked salmon clean out of the lake, and for an instant all its awful bulk hung in a huge curve, with the water streaming off it and the knife wrenched from Jeremy's grasp sticking in its underside.

"Take that, you brute!" shouted Nick as he blazed at it in mid-air, and three heavy bullets tore their way through the great mass of scale-clad flesh and bone before it fell.

Down crashed the terror, flinging up a wave that almost swamped the boat, then lay thrashing helplessly. Blood pouring from its wounds stained the clear water and hid everything beneath the surface.

As Nick stood with the pistol levelled at the writhing beast and his finger still on the trigger, Mort gave a shout. "Don't shoot! Don't shoot, Nick. There's Jeremy." And, dipping his paddle, he drove the boat towards the spot where Jeremy's head had just appeared above the foaming surface.

"Don't mind me," said Jeremy hoarsely. "The girl. Pick up the girl."

"The girl's all right," snapped Nick. "Catch hold."

"Get the girl," ordered Jeremy. "There may be another of those brutes about."

"I'll hold Marse Jeremy," put in Jake as he stretched out a skinny arm and grabbed Jeremy. "Yo' paddle, Marse Mort."

The great man-eating fish had sunk struggling into the blood-stained depths, and Mort, paddling with all his might, sent the boat across to where the girl still clung to her upturned canoe.

Nick caught hold of her and swung her into the boat. Then, without a moment's pause, he turned to help Jeremy.

"Is she all right?" questioned Jeremy anxiously, as with Nick's help he scrambled in over the stern.

"Nothing the matter with her," returned Nick harshly. "What about you?"

"Don't get cross, Nick," grinned Jeremy. "I'm all serene."

But Nick's sharp eyes had noticed a crimson stain spreading on Jeremy's soaked shirt sleeve. "You're not, you idiot. You're hurt!" he retorted. "Here, let me see your arm."

Jeremy's smile faded. "You leave my arm alone, Nick, and attend to business. Now that the light is not on them, those dwarf beasts are coming on like blazes. We've got to get out of this sharp. Look, the little lady is pointing us where to go.

"The water gate. She's saying something about a water gate," continued Jeremy. "Get your paddle out, Nick. I can tie my arm up and stop the bleeding. It's only a bit of a cut where the brute caught me as it turned."

Nick looked back and saw that Jeremy was right. The dwarfs, relieved of the glare which had blinded them, were coming on again full split. He waited no longer, but picked up his paddle and set to work.

The pyramid was shining out again in all its exquisite rainbow hues, and now that they were so much nearer to it, its size was paralysing. It bulked like a many-coloured mountain, towering nearly to the roof of this underground world. It stood about half a mile back from the shore of the lake, and the ground between it and the water was all bare rock. Nick saw that, if it was to be a case of landing and crossing this open space, it was all odds on the dwarfs catching them before they could find refuge.

Suddenly Jake gave a shout. "Dere's de gate! I kin see it right plain."

Nick saw it, too, a lofty affair of grey metal set between solid walls of black rock. A friendly light shone out between the bars.

Jeremy, who had twisted a handkerchief around his damaged arm, picked a paddle, but Nick turned on him like a flash. "Stop that!" he snapped. "Drop it, you idiot. Take your pistol if you like, but if you try to use that arm of yours I'll jolly well bash you over the head."

Jeremy glanced back at the dwarfs and saw that they were still a good way behind. "All right, Nick," he grinned. "I'll be good. But get a move on you, for I've had enough of those sling stones."

"Say, do you reckon they'll open those gates?" demanded Mort. "We'll sure be in a tight place if they don't. Ask the girl, Jeremy, if you can get your tongue to it."

Jeremy spoke to the girl in Old Egyptian, and a puzzled look crossed her pretty face. He repeated his question, then suddenly she laughed and replied in her sweet, ringing voice.

"What does she say?" asked Mort anxiously.

"She says it's all right—that the gate will be opened as soon as we reach it," replied Jeremy.

"De little lady am right. De gate's a-openin'," cried Jake, paddling like mad. "Oh, my golly, listen to dem owl folk!"

The owl folk, as Jake called them, seeing their prey disappearing, had burst into screeches of anger and disappointment, and the echoes of the great cavern, picking up their voices, sent them throbbing horribly into the unseen heights above. It sounded as if a pack of demon hounds were coursing overhead.

The girl, who up to now had been pluck itself, shivered and went pale; even Nick felt cold chills crawling down his spine. Sling stones began to hiss through the stagnant air, but they fell short, dropping into the still water with sharp flopping sounds.

And now the great gate had risen six feet clear of the water, and the boat, driven with all the power of three pairs of arms, shot through it and into a broad, rock-rimmed channel beyond. It was barely inside before the gate sunk back in its sockets, and as it locked again with a click there came from outside the hideous wailing shrieks of the dwarf folk.

Jeremy drew a long breath. "I'm not sorry to be out of that, Nick," he remarked.

"So long as we're not up against something worse," returned Nick gloomily. "You don't know what we may strike inside this glass house."

"I'm not worrying," laughed Jeremy. "Not if our little pilot is a specimen of the people inside. She's a dear."

"Oh, the girl's all right," said Nick grudgingly, "but it don't follow that the rest are cut to her pattern."

"We shall soon know, anyhow," replied Jeremy, "for I see another gate opening."

The channel or canal ran straight as a die towards the centre of the near wall of the amazing pyramid, which it entered through another gate of the same rustless grey metal. But this was even more massive than the first, and was beautifully ornamented with figures which both Jeremy and Nick recognised as purely Egyptian.

As Jeremy had said, this gate, too, was rising in the same noiseless fashion as the first. Another few strokes and they were through it and floating on the surface of a vast circular pool of exquisitely clear water. Down upon it beat a great golden light illuminating it to its lowest depths and showing up strange fish that swam within it, and turtle-like creatures creeping over the marble blocks which formed its bottom.

And all around was a scene of such exquisite beauty and such delicate splendour as left the four breathless, gasping with amazement.

The water of the pool brimmed level with a wide pavement of many-coloured stone, beyond which rose masses of the most exquisite trees and plants covered with flowers and fruit of every colour. Fountains played among them, and the tinkle of falling water broke the solemn silence of the huge place. The air was full of delicate scents.

But there was no time to take in the half of it, for the girl was standing up in the bow of the boat and calling to a man who stood on a flight of steps coming down to the pool. A tall, splendid-looking man whose high-arched nose and wide-set golden eyes made Jeremy think of an eagle.

He was dressed in a tunic of white which came to his knees and was edged with royal blue. "He is her father," explained Jeremy.

"I don't think you need be scared of him, Nick."

"He looks all right," allowed Nick, "but what price that blighter standing behind him?"

Jeremy glanced at the latter as the boat moved in towards the rim of the pool, and had to acknowledge that Nick was right, for if the first man looked like an eagle the second more nearly resembled a vulture. His thin nose was hooked like a beak and his narrow eyes held a fierce and sulky glare.

"Let's hope he's not so bad as he looks," he smiled. Then, as the boat came alongside the steps, he jumped up and gave his hand to the girl to help her out.

Sulky-face stepped forward quickly, snarling out some remark which did not sound complimentary, and pushing Jeremy roughly aside, tried to prevent his touching the little maid.

Jeremy, like most big men, was usually the sweetest-tempered creature, but this was a bit too much for him. He made a quick movement and stamped with all his weight on the sulky man's sandal-shod foot. Jeremy's boots were heavily nailed, and Sulky-face, taken completely by surprise, gave a yell of pain and hopped away on one leg, holding the injured foot in both hands.

"Sorry," said Jeremy smoothly, and took no more notice of the fellow. For a moment the girl looked startled, then she suddenly burst into the prettiest little trill of laughter, and even her grave-faced father could not keep back a smile. He stretched out his arms and the girl sprang to him.

Still holding her he spoke to Jeremy.

"I saw all," he said, and although the way in which he pronounced the Old Egyptian sounded odd to Jeremy, yet he quite easily understood the words. "It was a brave deed, and one greater than any done in Koom these thousand years past. Thou hast saved the life of Chalma, my daughter, and all that I, Phra, ruler of this place have, is thine."

"I thank you, sir," answered Jeremy with a very fine bow, "but I would have you remember that it was your aid and that of your daughter which saved us from the dwarf folk. So the debt is upon our side."

"Well and courteously spoken," responded the other. "Yet is the life of my daughter more to me than my own life, and in equal measure is my gratitude."

Mort who had landed and was standing close by broke in: "Say, Jeremy, don't keep it all to yourself. What's His Highness giving you?"

"We are just exchanging the compliments of the season," Jeremy answered with a smile. "He is pleased to see us. This place is called Koom, his name is Phra, and the princess is Chalma. That's all so far."

"I jest knowed she was a princess," declared Jake. "No common gal could be dat pretty and sweet."

"What doth the boy say, whose face is like darkness?" asked Phra, and when Jeremy told him he smiled. "Truly ye do come from a country of courtesy," he said. "But your journey from the upper world was without doubt long and tedious and your bodies are worn with travel and hunger. Food is prepared. Will ye eat?"

"Indeed we will, sir," answered Jeremy, "but first, if it pleases you, we would desire to make ourselves clean."

The chief clapped his hands, and the boys got a fresh shock. From among the trees there glided silently two of the oddest figures possible to imagine. They were as short as the dwarfs but not nearly so burly; also their eyes were not so large, nor their ears so pointed. But the queer thing was that they had no more expression in their faces than two china dolls, and that they moved with quick little jerky steps, just as if they had been wound up.

Jake stared at them with popping eyes. "Marse Nick." he demanded, "is dey real men or does dey go by machinery?"

"Blessed if I know, Jake," replied Nick. "You'd better ask Mr. Jeremy."

"Sort of Robots I'd say, Nick. But it's a puzzle we shall have to solve later," said Jeremy. "For the present they are going to take us to have a wash, and after that there's a meal waiting."

The Robots led the way up the steps, along a broad walk bordered, like the great pool, with most exquisite plants, and into a small square room, the walls of which were of the grey metal which seemed to take the place of both wood and steel in this underground world. One moved a lever in the floor and the room began to ascend.

Nick gave a sort of groan. "A lift! A perfectly modern lift! And in a hole in the earth in Central Africa! This is the absolute limit!"

"What's biting you, Nick?" demanded Mort. "If they've got electricity, why shouldn't they have lifts?"

"But how do they get it? Where's their power?" asked Nick despairingly. "I shall jolly well go crazy if I don't get to the bottom of it soon."

The lift stopped, the Robots opened a door, and they were in a wide corridor with walls and floor of coloured glass. Another door led into a magnificently appointed bathroom, in which a great pool brimming with crystal-clear water occupied the centre, while around was a tessellated pavement and dressing-rooms fitted with deep luxurious couches.

"This is the goods," exclaimed Mort, beginning to strip in a hurry. But when Jeremy tried to get his shirt off it was stuck to his arm with dried blood.

"Steady on, you old idiot!" said Nick sharply. "In all this excitement I'd forgotten your arm. Let me sponge it and tie it up for you."

He pointed out the wound to one of the Robots. "Get me a bandage," he said, making a twisting motion with his fingers, and the queer little creature moved silently away. "Rum little objects!" said Nick. "Think they can talk, Jeremy?"

"I'm sure I don't know. But he understood you right enough, for here he is with the bandage."

"Yes, and a pot of ointment, too. By Jove, how queer it smells! Think it's all right, Jeremy?"

"I'll chance it," said Jeremy; then as Nick put it on an expression of amazement crossed Jeremy's face. "It's taken the pain out like magic," he exclaimed, "and I tell you it was hurting quite a lot. My word, there'd be a fortune in this if we could put it on the market at home."

"So there would in this bath," called Mort, who was splashing in the pool. "The water makes you feel like new. Come on in."

Mort was right. There was something in the water which braced them up in an amazing way, and made their skins feel like silk. By the time they came out their clothes had been brushed and cleaned by the Robots, and fresh underwear of a stuff like very soft white silk was ready for them.

"We're sure on velvet, Nick," said Mort as the Robots took them down again in the lift.

But Nick shook his head. "How do they do it?" he growled. "The whole business beats me."

Phra and his daughter were waiting in a wonderful banqueting hall, and with them about twenty others, some men and some women. They were all tall and slightly built, and although their features were somewhat Egyptian in shape, their skins were marvellously fair. Pleasant, smiling folk all of them, with only one exception. That was Sulky-face, who scowled horribly at the newcomers. His name they found presently was Nartas.

Phra introduced his guests and the boys bowed in their best form. The pyramid people greeted them by raising their hands over their heads, then slowly dropping them to their sides.

The Princess sat at her father's right, Jeremy at his left. The others were on either side. Then a number of the Robots came in with the dishes, and served them just as well-trained British servants might have done. The food was delicious, but every bit of it brand-new to the boys. Jeremy was aching to ask questions, but as his host did not speak, thought he had better wait.

It was Jake who broke the silence. "I done tole you dis was Hebben," he remarked, showing all his ivories in a delighted grin.

"I'll allow it's a mighty good imitation," agreed Mort.

Phra asked Jeremy to explain, and laughed outright when Jeremy told him. Then his face changed. "There was a time when my people lived in a state as near Heaven as any mortals could hope for," he said sadly, "but now, alas, all is changed, and year by year our numbers diminish and dangers thicken around us."

Jeremy looked up quickly. "The dwarfs, sir. Are they your enemies?"

"They are our mortal foes," responded Phra solemnly. "Listen and I will tell you how these misfortunes came about. Three thousand years have passed since my forefathers, flying before invaders from the East, discovered this under-land and founded here the city of Koom. In the caverns lived the People of Night whom you call the Dwarfs. My forefathers subdued them and made them slaves, and with their aid built this mighty pyramid.

"In those far days there was free access to the world above, and the oasis of Feshan blossomed like a rose. Then came the day of fire. The land split and molten rock gushed out, covering our gardens with a dreadful flood, and breaking down the upper ways so that none below could escape.

"But, so our records tell us, there were great stores of grain in Koom, and already our people had learned certain secrets of preparing food from the cave growths. So when the terror had passed those that still lived took counsel together and planned to save themselves. They harnessed the earth forces, set the great lights in the roof, and by means of the earth current increased the crops of the under-land. And so through many generations they toiled and did many mighty works and came to great pleasure and happiness."

He paused. The great room was perfectly still, everyone listening intently.

"My friend," he went on, "thou hast heard of the ant folk that have forced other ants to toil for them, how that these greater ants, by failing to perform needful toil, have become so feeble that without their slaves they starve? So it was with us. We came to depend too greatly upon our slaves, and lost the art of lighting and working for ourselves. Also we began to diminish in numbers.

"Then certain slaves who had fled from servitude to the Outlands and to the Lower Levels took arms against us, and we were helpless to defend ourselves. We were driven back until we were forced to entrench ourselves in this central stronghold, and here we live, holding out against the evil powers that surround us."

He paused again. Jeremy, almost breathless with excitement, turned to Nick and in a few rapid words told him and the others Phra's amazing story.

"Earth force," repeated Nick, "electricity he means. But where do they get their power? They have no coal. There's no fall of water for turbines. Ask him, Jeremy—ask him."

At this moment one of the quaint little Robots approached and handed Phra a slip of paper, on which words were written in the old hieroglyph script.

Phra glanced at it and at once rose to his feet. "Others are entering the under-land," he told Jeremy. "It may be that thou can'st say who they are. Come with me, thou and thy friends to the Great Mirror."

Jeremy translated and Nick whistled softly. "Bastin," he said. "Ten to one it's that blighter Bastin and Kasim with him."

The great lift took them soaring into the very summit of the pyramid and here they entered a darkened chamber in the centre of which an immense mirror lay like a pool of dim light. Two attendants stood by, poring over it. Phra stepped across to the mirror and the others followed.

One of the attendants moved a screw, the light strengthened and the boys found themselves gazing down at a scene which was strangely familiar. There was the great slope stretching to the swift river and covered with curious growths, the giant wall of rock, and the archway through which they themselves had entered a few hours earlier into this amazing under-land.

"It's a miracle," exclaimed Nick. "How do they do it?"

"Something on the camera obscura lines," said Jeremy. "Sort of thing they show you at Blackpool and Margate."

"Blackpool be blowed," retorted Nick. "They can only show you something quite close at hand. This place is miles away. It must be another of their wireless stunts."

"Never mind how it's done," said Jeremy, "it's what is being done that matters. Look at those two chaps skulking among the bushes."

"Bastin and Kasim," snapped Jeremy. "I knew it."

Phra saw them too. "What white man is this?" he asked of Jeremy.

"One who came with us from the West, sir," Jeremy answered. "A man with much knowledge of science, but greedy for money and power."

Phra nodded slightly, then taking a kind of magnifying glass from the attendant examined the picture more closely. He turned to his daughter. "The other is Kasim," he said quietly.

Jeremy caught the name. "Kasim. How do you know it is Kasim?"

"Because he is one of our people," replied Phra with a touch of bitterness.

"One of your people!" exclaimed Jeremy in amazement, "but he has been with us on our journey across the desert from Egypt. He posed as Bastin's servant. How did he get out of the caves?"

Phra's handsome face went suddenly grim. "I would that I knew," he answered. "The man is a traitor and in league with our enemies. Nearly a year ago he left Koom by stealth, and all here believed that he had been killed by the Night Folk. But now his purpose is clear. He hath made alliance with this Bastin and brought him here to fight against us, hoping no doubt that by his science he may prevail. What thinkest thou? Am I right?"

"I greatly fear that you are, sir," responded Jeremy gravely. "I will ask my friends what they think."

"You can bet he's right," said Nick, as soon as he understood. "I never trusted Bastin from the first minute I set eyes on him, and as for Kasim, there's something absolutely inhuman about him." He turned to the mirror. "He's in with the dwarfs all right. Watch 'em, Jeremy!"

A crowd of hideous Night Folk had suddenly appeared from the direction of the river, and as they approached Kasim stepped out to meet them. At once they all dropped to their knees. Kasim pointed out Bastin and began to harangue them.

Nick stared at the mirrored scene with fresh amazement. "Gad, you could almost fancy you hear what he's saying," he exclaimed. "But doesn't he know he's being watched? Ask Phra, Jeremy."

"Thou art right. It is certain that Kasim knows," Phra told Jeremy. "Yet he cares not."

"But if we can see him, can't we get at him?" demanded Nick impatiently. "Surely to goodness these people can do something with all their electric power!"

Jeremy questioned Phra, but the latter shook his head gravely.

"Our weapons are of defence, not offence," he answered. "It is against our law and custom to take life."

When Jeremy explained this, Nick snorted. "What rot!" he said scornfully. "I hope he doesn't expect us to be bound by any silly rules of that sort. You can tell Phra from me that, if I get the chance, I shall wipe out those two treacherous hounds as quickly as I would a couple of vipers."

"I don't think I'll tell him that just yet," replied Jeremy with a crooked smile, "all the same, I shall be with you when the time comes. But watch what is happening."

The mirror showed the dwarfs waving their spears excitedly. Then they escorted Bastin and Kasim down to the river, and into boats. The boats turned up-stream, being driven powerfully against the current. In some mysterious way the mirrored picture followed them, giving the whole journey as plainly as it might be shown on a cinema screen.

For a long time those around the mirror watched in silence while the canoes were forced up long rapids which ran between high walls of rock. Sometimes others of the dwarf people were seen standing on the rocks, and once a hideous snake-like head peered furtively over the rim of the river to draw back at once and vanish.

At last the picture began to dim. A veil of darkness fell across it, and in a little while the whole thing faded clean out.

Nick looked up.

"What's happened now?" he demanded.

Phra seemed to understand. "They have passed beyond the great lights into the Out-lands," he explained to Jeremy. "Into that country we cannot follow them."

Jeremy whistled softly. "Then how do they see to find their way?" he questioned.

"By the light of the underworld fires," was the strange answer. "And there they will hatch their plots against us and against Koom."

Jeremy translated literally for the benefit of the others. Nick looked thoughtful, Mort uncomfortable, but only Jake spoke. "I nebber knowed afore dat Hebben was so near to de bad place," he remarked pensively.

Two days later Jeremy was standing over the mirror in the observatory with Chalma beside him. Nick was somewhere below, making the rounds with the engineers.

The observatory fascinated Jeremy, and he spent hours there, watching the strange life of this underground world, but above all, keeping a keen look-out for Bastin. The grave-faced attendants at the Mirror had come to know the big, young Britisher well, and although he could not yet talk to them, still by signs he and they told one another many things.

They had pointed out to him the delicate mechanism by which this marvellous business was worked, but Jeremy had not yet managed to grasp the secret. All he did understand was that discs of the rare metal selenium were used, and that by a wonderful development of wireless any part of the cave that was within range of the great lights could be watched and studied.

With Chalma it was different. She spoke the ancient Egyptian language perfectly and was rapidly picking up English words. Her quickness was simply amazing.

Just at present Jeremy was studying the immediate surroundings of Koom; the lake, with its broken cliff brooding over its glassy depths, the river and the great rock plateau on which the mighty pyramid itself stood.

Where the river left the lake on the lower side a great dam of solid masonry lay across it, and the water fell over this in a sheet of white foam. Jeremy knew already that the dam had been made by the people of Koom so as to raise the level of the lake sufficiently to fill the pyramid pool from which the wants of the pyramid dwellers were supplied.

Below the dam the river ran deep and still for some little distance, then was joined by a tributary stream which came out of a big pool lying close under the eastern wall of the cave. This pool was four or five acres in extent and lay deep and dark under high banks. Its nearer side was less than half a mile from the pyramid itself. Jeremy noticed now that there were sluice gates at the mouth of the pool, and he pointed them out to Chalma. "What are they for?" he asked.

"To keep Krah in his prison," answered the little Princess in her sweet, flute-like voice.

"Who is Krah?" questioned Jeremy quickly.

Chalma's pretty eyes widened. Then she laughed. "I forget that you have been here so short a time. Krah is—well he is just Krah."

"That is not much of an explanation," smiled Jeremy.

The Princess spoke to one of the attendants, and he left the room. "He is going to fetch a picture of Krah," Chalma said. "That will explain better than I can tell you."

The man came back with a roll of parchment which he spread out before him. On it was beautifully painted a creature so startling that Jeremy stared at it for some moments in wide-eyed amazement. It was a vast, lizard-like beast with an enormous body, a terrific head, fanged jaws, and a long scaly tail. Down its back ran a sort of frill and its head was ornamented with two great spikes. Its colour was a dull yellow shading into lurid green.

"You have never seen one, Jeremy?" asked the Princess.

"Never, except in bad dreams," responded Jeremy, "but it looks to me like a beast whose fossilised bones have been found up above and which they call the brontosaur."

"What does that word mean!" asked the Princess.

"Thunder lizard," said Jeremy. "Not that thunder means much to you, for you have never heard it down here. But surely you don't mean that you keep a thing like that as a pet?"

"There are two," Chalma told him simply. "And they are old—oh, so old! But I do not think they are quite pets."

"This one doesn't look much like it," agreed Jeremy with a slight shiver. "But tell me why these monsters are shut up in the pool."

"It had to be," the girl said. "Once they lived in the lake and caused great trouble to all. No boat was safe, and many of our servants were drowned or devoured. Some of the Council desired to kill the creatures, but even then our people were against the shedding of blood. Also, these were the last of their kind in the under-lands. So the water gate which you see was built, then the great creatures were tempted with baits up the little river and into the pool. And when the gates were shut they could no longer harm us."

"Jolly smart, I call it," said Jeremy in English. "But there is one thing I don't understand, Princess. How do you feed them? I bet they don't live on mushrooms."

Chalma laughed.

"No, indeed, Jeremy. Yet the matter is simple. Once in each three months the great blind fish come up the river to the lake. In hundreds they come, and many swim up the side stream to the pool. At such times the sluice is raised and Krah and his mate find plentiful food."

"I'm glad I don't have to wait three months between meals," said Jeremy. "I have one more question, Princess. Seeing that no one is allowed out of the Pyramid, how are the sluices raised?"

"By means of the earth force," Chalma answered. "There is no need to go outside. Yet at times my father and a few others visit the great pool, for the land being almost surrounded by water is not easily approached by the People of the Darkness. So when the keeper of the Mirrors tell us that no enemies are near we safely venture out."

"Then I'm jolly well going out to see next time Krah and Co. are fed," declared Jeremy. "When is the monster's next dinner date?"

"It is soon," answered Chalma. She spoke to the attendant. "Two sleeps from now," she told Jeremy.

"Good business!" said Jeremy. "Tell your father, Princess, that we must see Krah feasted."

Chalma made a little face. "It's not pleasant to see," she said. "Myself, it hurts me to watch the poor fish being swallowed by the monsters."

"I've swallowed too many myself, for that to worry me," said Jeremy. "And, talking of food, it's just supper-time. Shall we go down, Princess?"

"Just like a man—always wanting to eat," laughed the girl as she led the way to the lift.

The visitors' meals were served in Phra's own apartments, and Phra himself, if very much a king in public, was the kindest and best of hosts in private. Much to the amazement of the boys, they found that he was not altogether ignorant of what went on in the upper world of sun and wind. How, he never would explain, but Nick's opinion was that, by means of their delicate instruments, the people of Koom had caught and deciphered the wireless signals of the nations above. At the same time, Phra was intensely interested in all that the boys could tell him of modern civilisation and asked endless questions. It was easy to see from whom Chalma got her clever brains and quick mind.

This evening, however, it was Jeremy who asked questions, and he soon had Phra's promise that the next time Krah and his mate were fed he and the others should be allowed to watch the performance.

"But only if all is quiet," said Phra firmly. The boys looked at one another. No one spoke, but all had the same thought. How long would there be quiet in this underworld, with that evil beast Bastin plotting out there in the darkness?

Bastin, however, made no sign, and two days later news came from the Watch that the big fish were running up the river. An hour later Phra and his daughter and the four boys were ready to start.

A crowd watched them out. So very rarely was the great door of the Pyramid opened that the event caused a ripple of excitement among the dwellers in Koom. Among the people Jeremy noticed Nartas scowling at him sourly. He felt the man's hatred like the heat from a fire, yet knew that he feared to show it openly. But if trouble arose Nartas would be on the side of the enemy, and a traitor in the Pyramid might do desperate harm.

"What's up, old bean?" asked Nick. "You look as if you'd lost half a crown and found sixpence."

"Tell you later," answered Jeremy. "After we've seen the Zoo."

It was only a few minutes' walk across to the sluice gates, which were made of the same indestructible grey metal as all similar work in Koom.

"Gee!" cried Jake, his round eyes rolling with excitement, "jest look at them fish!"

"Some fish!" agreed Mort. "Say, they're as big as porpoises!"

The river was full of great black backs, rolling above the surface as the blind fish nosed at the sluice gates in a vain effort to pass through.

"Just like salmon working up to their spawning beds," said Nick, as he stared down at the shoal.

"Not much like salmon to look at," replied Jeremy. "See their long whiskers. They're more like giant catfish than anything else."

Chalma touched his arm. "Look," she whispered, and pointed towards the pool. The pool lay deep and dark under high walls of dusky rock, but now its glassy surface was stirring, and out of the depths rose slowly a head. A head so huge and terrible that the boys held their breath as they watched, and even Phra and Chalma stood silent. Mort was the first to speak. "Say, Nick, pinch me, will you?"

"What for?"

"So as I'll be sure I ain't dreaming."

"Don't be an ass," Nick grunted. "All the same, I'll allow it is a bit hard to believe one's eyes."

"It is like the picture, is it not?" said Chalma to Jeremy.

"Yes, but so big," replied Jeremy hoarsely. "Heavens, the thing must be sixty feet long."

"And here is his mate," said Chalma, as a second and somewhat smaller edition of the first monster rose sluggishly beside him. The two swam towards the gates, and Mort, although he and the others were standing quite thirty feet above the level of the water, stepped hastily back.

"They will not molest you," Phra told him with a smile. And at that moment the sluice gates slid apart, and the huge black fish crowded blindly into the pool.

Chalma put her hands before her eyes, but the boys stared in silent horror as the monsters made their meal.

"Like sardines," muttered Nick in a half-suffocated tone, and just then the light overhead flickered oddly. Phra watched the flickers, then turned to the others. "It is the signal to return," he told them, and went quickly back.

"Bastin, I'll bet," said Nick to Jeremy. But when they got in they were told that all that had been seen was a canoe with four of the Night Folk coming up the river from below.

In the embrasure of a great window, many hundreds of feet above the rock floor of the Cave country, the four sat together, looking out across the wide lake that slept under the everlasting lights. That is, three of them were looking out, but Mort was busy with a little pocket-diary and a pencil.

"I say, boys," he remarked suddenly. "Do you know we've been here four weeks to-day?"

"I'd almost forgotten we'd ever been anywhere else," smiled Jeremy. "But one might spend four years and still find something new. It's a wonderful show, isn't it?"

"Top hole," agreed Nick. "That power plant alone is quite the most amazing thing I've ever imagined. I spent hours down there to-day with the engineers."

"They've tapped the central fires, haven't they?" asked Jeremy.

"Yes, a double shaft, three miles deep. They run the water of the lake in by one, and the steam comes up the other."

"Three miles deep!" exclaimed Mort. "Say, how did they do it?"

"Don't ask me. But they're extraordinary people; and, in science and chemistry, miles ahead of any of our folk. No wonder Bastin is keen to collar their secrets."

"Has he been seen since he went off into the Outlands?" asked Jeremy.

Before anyone could reply, Jake gave a sudden exclamation, and pointed across the lake.

"Dere's some ob dem owl folk," he announced.

A large boat slid silently into sight near the far side of the lake. Nick took up a pair of grey metal field-glasses and focused them. "Twelve men in it," he said presently. "And all masked. Take the glasses, Jeremy, and look at those two in the stern."

Jeremy looked, then as he lowered the glasses there was an odd expression on his face. "Those two are bigger than the rest," he said.

"They're Bastin and Kasim," said Nick, with decision.

Jeremy nodded. "That's what I think. What devilment are they up to?"

"If we'd only got a gun!" growled Nick. "An ordinary field-gun with an H.E. shell would fetch 'em first pop. And these 'tiffies in the Pyramid could turn guns out as easy as winking."

Jeremy shrugged. "But they won't. According to Phra it's about a thousand years since they last killed anyone."

"And that's why they live shut up here like beetles in a box," sneered Nick. "Well, there's going to be some killing if Bastin tries any monkey tricks. We've got one perfectly good pistol."

"I wonder what arms Bastin has," said Jeremy thoughtfully.

"If he hasn't got them he'll make them," replied Nick. "Those dwarfs know a thing or two. They manufacture their own boats, so Phra told me, and you all saw how smart they were with those slings."

"Dat Bastin, he can't get into dis hyah glass house?" cried Jake in a fright.

"He'd have a job," allowed Nick, "but it's in my mind that sooner or later he means to do just that. What do you think, Jeremy?"

"I don't think. I'm sure," replied Jeremy. "I haven't travelled all across the desert with Bastin and Kasim without getting to know just what sort of brutes they are. I told your father as much, Mort, but he wouldn't listen to me."

"Dat boat is gwine right across de lake," broke in Jake.

Nick raised his glasses again, "Jake is right," he said. "I wonder what their game is."

"One mighty good thing, they can't sneak up in the dark," remarked Mort Bradby.

Jeremy glanced at his watch. "Do you know it's nearly eleven?" he said. "It's been night for four hours up above. And it's sleeptime here. Hadn't we better turn in?"

"You take a snooze, Jeremy," said Nick. "I'll wait a bit. I've a notion that one of us ought to be on watch."

"Then will you call me when you want to sleep?" asked Jeremy.

"I'll call you all right," answered Nick, and Jeremy followed by Mort went off to their luxurious sleeping quarters.

Jeremy was dreaming happily of his home in Dorset when he was rudely wakened by a violent shake. Nick stood by his bed. "What's up?" asked Jeremy sleepily.

"Come and see," said Nick curtly and, barely awake, Jeremy found himself with his chum in the great lift shooting soundlessly up into the heights of the Pyramid. In a few moments they stood in the darkened chamber by the Great Mirror.

"Look!" snapped Nick, and Jeremy looked. There was a glimmer of quiet water, a boat—the same they had previously seen. It was tied to a ring bolt in a rock, beside an enormous dam of solid masonry.

Its crew were out on the dam and busy as bees under the direction of two men who, now that their masks were off, could be recognised as Bastin and Kasim.

"What are they doing?" asked Jeremy.

"They are going to blow up the dam," Nick answered.

"Blow up the dam—what dam?"

"The one at the far end of the lake, the one that holds the water at its present level."

Jeremy turned his eyes on Nick's face, and saw that his dark eyes were burning with anger and excitement. "But—but—" he said thickly, "that means—" he stopped.

"It means," said Nick, speaking very quietly, but very distinctly, "that the water will no longer flow into the Pyramid Pool, or from there into the great shaft. It means that, within a few hours, all our power will be cut off and that we shall be left in utter darkness, without lifts or any machinery working. It means death to everyone in Koom, ourselves included."


CHAPTER III

AS the last words left his lips Nick turned, and was swinging towards the door, when Jeremy stopped him. "What are you going to do?" questioned Jeremy.

"Something—and quickly. At any rate, I am not going to sit here and wait for the end."

"Of course not, but have you a plan?"

"There's no time to make plans. We four are the only fighting men in Koom, and it's up to us to stop Bastin's game. My notion is to have the lights turned out, take a power boat, slip across the lake in the darkness, and simply go for Bastin and Kasim. If we can scupper them their jig is up, for by themselves the Owl Folk can't do a thing."

"And suppose Bastin gets us first?" suggested Jeremy.

Nick shrugged. "It'll be a quick finish."

"Yes, for us, but what about Phra and Chalma?"

"We can't help it," groaned Nick. "Come on, there's no time to waste."

Jeremy glanced at the mirror. "Go slow, Nick. There's no great rush. That dam is solid masonry, twenty feet thick, and the stone is the hardest granite. It'll take Bastin hours to drill it, even if he is not interfered with."

"But we must interfere," exclaimed Nick.

"Of course we must, but for goodness' sake let us do it sensibly. Things are bad, I admit, but they are not quite so bad as you imagine."

"How do you mean, Jeremy?" snapped Nick. "Have you any better plan than mine?"

"I think I can improve upon it. You see, it is not as if we hadn't had any warning, for ever since Bastin arrived I've been expecting something to happen."

"So have I," interjected Nick, "but what could one do? I did try to get some of the Robots to make me a pistol, but either they couldn't or wouldn't understand. And as for these Koom folk, barring Phra and Chalma and one or two others, they're no better than sheep. Talk to 'em of guns or bombs and they go green and nearly faint."

"I had the same trouble," agreed Jeremy, "so I got Phra to give me the run of the Museum, and there I found several things that are going to be handy."

"What things?" asked Nick eagerly.

"Crossbows which will shoot almost as well as rifles, and some most excellent armour. Grey metal stuff, light as a suit of tweeds, but quite enough to turn sling stones or arrows."

"Good business!" cried Nick. "I might have known you'd do something useful, Jeremy. You're the only one of us with a head on his shoulders."

"Nonsense, Nick! You have twice my brains, but this is no time to swop compliments. You go and rout out Mort, and I'll ring up Phra if they haven't told him already. Then I'll get my armour and the bows and meet you below."

"What about Jake?" cried Nick.

"Use your own judgment. The boy's got pluck, but he's jumpy. I don't know whether he'd be much use on a trip like this."

"Better bring him. It'd break his heart to be left behind," said Nick, and was gone like a flash.

Jeremy turned to the attendant at the Mirror, a tall, quiet-looking man, named Nath. In the past month he had learned to talk with him. Now he asked him quickly if he had warned Phra. "I have spoken with the attendant at the door of his chamber," Nath answered, "but Phra himself hath not yet replied."

"Call again," said Jeremy. "You see what is happening, Phra must be roused at once."

As Nath stepped to the curiously-shaped receiver a tiny bell rang. "There he is," exclaimed Jeremy, and next moment a voice came clearly to the ears of both. "Phra sleepeth," it said, "and cannot be awakened."

"What does he mean?" demanded Jeremy. "Ask him, Nath." Nath spoke, and the answer came back. "Phra sleepeth as one that hath drunk of the poppy. The men of medicine are with him, but cannot rouse him."

"Crumbs, he's been drugged!" gasped Jeremy. "This is the limit." He strode towards the door, then turned. "Nath, keep us informed as to what goes on at the dam. You understand what is happening."

"Alas, my lord, I understand too well," said Nath quietly. "Be sure that I will do all that is in me to help."

Jeremy hurried to the lift, and in a few moments was at the door of Phra's suite of rooms. Chalma met him. Her charming face was full of trouble. "My father cannot be wakened," she told him.

"Drugged, I'm afraid," said Jeremy swiftly. "See here, Chalma, that scoundrel Bastin has a force of men at work on the dam. It is quite clear that he means to blow it up, and by so doing lower the level of the lake and leave us without power. We must stop him, and, since your father is unable to help us, I rely upon you to let us out of the Pyramid."

Tears were in Chalma's eyes, yet she braced herself bravely. "Alas, Jeremy, I have not the keys. They are in the hands of the Captain of the Night Guard."

"Who is that?" asked Jeremy.

"Nartas," Chalma answered, and Jeremy felt that he had known it before she spoke. His strong jaw set. "Princess," he said, "it would be wrong if I did not warn you that we are in a tight place. Myself, I believe that Nartas is in league with Bastin, and is responsible for drugging your father. Listen now, I am going down to rejoin Nick and the others, and if Nartas refuses to give up the keys we shall take them by force."

Chalma went very pale. "But Jeremy, that is what he will be expecting, and it may be that he is prepared."

"How—prepared?"

"He may use the Earth Force against you."

"Nick knows about that. He will be ready, and, if Nartas makes a move towards those buttons, he will be shot at once."

"It will be no more than he deserves," replied Chalma bravely. "But, Jeremy, what are you going to do?"

He told her briefly, and she went very pale again. "You will be careful, Jeremy," she begged.

"This is no time to be over-careful, Chalma," replied Jeremy gently. "But remember, we are going to wear the armour, and we shall have a Power Boat which is much faster than any canoe. Don't be afraid, dear. We shall come out on top."

In spite of his words, Jeremy's spirits were very low as he collected his armour and weapons, and with three Robots carrying them, made his way down in the great lift. The fact that Nartas was in charge of the Night Guard made him feel certain that the whole thing had been planned out beforehand. He had fully made up his mind, if it came to the push, to shoot down Nartas, but it was possible that the man had accomplices in the Pyramid, and no one could prophesy what would happen once fighting began.

As he stepped out of the lift, Nick was there with Mort Bradby waiting. "I say, Jeremy, Nartas is in command," said Nick swiftly.

"I know. Where is he?"

"I've sent for him. Ah, there he is coming."

"Watch him," whispered Jeremy. "Chalma says that he may try the Earth Force on us—electrocute us, she means. But you know where the switches are, Nick. If he moves towards them, warn me at once, and I shall shoot him."

Nick nodded, and next moment Nartas was with them. To Jeremy's surprise, the man's unpleasant face was not so sour as usual. It bore a distinctly anxious expression. "I have received the message from the observatory," he began at once. "And that Phra sleepeth and cannot be wakened. What wish ye to do, oh strangers?"

"We want a Power Boat—the biggest and fastest there is," Jeremy told him bluntly. "And the key of the Water Gate."

"Is it that you desire to fight against these invaders?" questioned Nartas, with a sideways glance at the armour and weapons carried by the Robots.

"That is our intention," Jeremy answered. "Have you any objection?"

"Far be it from me to prevent you in this matter," was Nartas' astonishing answer. "I will give orders that the Power Boat be prepared, and the Water Gates opened against your going."

"Bit too good to be true," whispered Nick to Jeremy as Nartas went off. "The pie-faced blighter has got something up his sleeve."

"You're probably right," said Jeremy, "but so long as we get the boat we're all right. Nath and his crowd up top side will see to the lights being dowsed."

"Say, if there's no light, how'll Bastin carry on?" drawled Mort.

"Don't you worry about Bastin, Mort," retorted Nick. "You can lay your last dollar that he's fixed himself up all right."

"Where's Jake?" asked Jeremy.

"Coming, I guess," Mort answered. "He hadn't finished dressing when I started down." Jeremy pointed to the armour which the silent little Robots carried. "Time we got into our togs," he said. "Here's your lot, Nick."

Nick looked doubtfully at his coat of grey mail, but when he had slipped it on was much relieved. "Fits like a glove," he said. "And no weight to bother one. Now for the helmet. Why, it might have been made for me," he added.

"It was," said Jeremy. "Or rather it was altered to fit you. Now you, Mort." In a very few minutes they were all fitted up. Jeremy had provided swords as well as armour. These were of steel, tempered in some astonishing fashion, and had edges like razors. "They're at least a thousand years old," Jeremy said, "yet yesterday I cut through an inch of the grey metal with mine and never even turned the edge."

"I don't reckon I can do a lot with a sticker," said Mort, "but this bow-shooter sure takes my fancy. I used to be hot stuff with a sling shot when I was a kid."

"A catapult, you mean, I suppose," grinned Nick; and just then their Power Boat came gliding silently up to the marble steps.

"All aboard!" cried Mort, and Jeremy glanced approvingly at the American boy. Small and slight as he was, he had plenty of pluck, and would be all there when the time came.

Nartas came up. "The craft is but small," he said to Jeremy, "but it is the speediest of all. Dost thou understand how to control it?"

"I don't, but Nick Prest does," Jeremy told him. "Get in, Mort."

Nick was already at the controls and the two followed him in. Several of the Robots were busy with the levers of the Water Gate which was beginning to roll up. At the last minute a figure came running from the direction of the lift. "Here's Jake at last," said Mort, as the boy, his black face almost hidden by the vizor of his helmet, sprang lightly into the launch. "Say, Jake, where did you get your armour?"

But Jake either did not hear, or, at any rate, he paid no attention to the question. He was stowing his crossbow out of the way into the stern sheets as the launch darted forward across the inner pool.

Jeremy glanced once at the sheet of clear water with its exquisite marble steps, and the masses of luxuriant flowers and foliage surrounding it, all glowing under the soft lights. Then he gave a sharp order and in an instant the great lights dimmed, sank, and were gone, leaving everything plunged in impenetrable gloom. A second later, and there burst out from the towering summit of the Pyramid the stabbing, blazing ray of the great searchlight. Following under its radiant beam, the launch shot through the gates and down the channel towards the lake.

"I wonder if we shall ever come back," was the thought that flashed through Jeremy's mind.

The second pair of gates giving upon the lake opened to let the launch pass, then the long, slim craft was speeding across the surface of the water. The searchlight blazing full upon the dam gave Nick his direction and showed up Bastin and his gang swarming like bees on the summit of the great bar of granite masonry.

"Mighty cute notion, that of Bastin's—those masks," said Mort. "There ain't a lot he don't think of, Jeremy."

"Not a lot," replied Jeremy grimly. "But what I'm wondering at this moment is whether he is expecting us."

"How would he?" questioned Mort. "He certainly can't see us."

"He can't see us," agreed Jeremy; "but the odds are that Nartas has warned him."

"That chump! Why, he was polite as pie."

"Too polite, by half," said Jeremy. "If you ask me, it's a bit more than a coincidence that Nartas is on guard the very night that Bastin gets to work."

"That's what's been worrying me," agreed Nick. "My trouble is, I can't see the bottom of this plot."

"Take it from me, we shall find out before we're a lot older," said Jeremy. "My own notion is that he thinks that Bastin's crowd are too strong for us, and that he is simply handing us over to them."

Nick gave a little bark of a laugh. "If that's his notion he's liable to be mistaken. This boat isn't like a canoe. She's good for nearly twenty knots, and we can run rings round Bastin's crowd. But see here, Jeremy. You are boss. What are the orders?"

"Go quietly till quite close, then speed up and swing in near to the dam. Every one of us shoots to kill Bastin, and if we succeed then we try for Kasim. Nick, you take the pistol, for you'll only be able to use one hand. The rest of us use the crossbows. There's a box of bolts here amidships. They're steel-pointed, and, at close range, will kill like rifle bullets."

There was silence for a few moments as the launch sped onwards. Her electric engines were absolutely noiseless, and Nick had now left the path of the searchlight ray and was running as near as he dared to the cliffs at the edge of the lake.

"They haven't spotted us yet," muttered Nick presently.

"You can't tell," said Jeremy. "Even if Bastin did know we were coming he'd keep his men at work as a blind. But we had better not talk too loudly. Sound carries like the mischief in this still, heavy air."

By this time the launch was so close to the dam that every detail stood out like a moving picture in the white glare of the great searchlight. There were at least fifty of the hideous Night Folk on the great wall of masonry, and the ring of sledge hammers on chisels echoed weirdly among the mighty cliffs which bore up the roof of the under-world.

At the foot of the lake the cavern was much narrower than at the head. Behind the dam the ground rose in a slope thickly covered with moss bushes, a slope which grew steadily steeper until it ended in the sheer cliff bounding the western side of the cavern.

Jeremy leaned forward and whispered in Nick's ear: "Can you see Bastin?"

"I can't, and that's just what's worrying me."

"Then hold up a minute, and let her drift. It's no use slaying the Owl Folk. Bastin's our game."

Nick nodded and switched off the power, and the launch drifted idly close under the steep shore of the lake. The Night Folk worked busily. They looked utterly inhuman under the blinding glare of the great light.

Jeremy hated the waiting, for it gave him time to realise the fearful odds against them. In spite of his tremendous strength, both of body and mind, he could hear his own heart thumping. His thoughts went back to Chalma and her father, and it appalled him to know that he and his three companions were all that stood between them and a terrible end.

At last a tall figure was visible for a moment among the workers clustered on the dam. Jeremy nudged Nick. "There he is," he whispered. "Push on, Nick."

Nick switched on the power, and the launch shot forward. Jeremy and Mort snatched up their crossbows and loaded them. The pistol lay ready to Nick's hand. "Steady, Nick," muttered Jeremy. "The beggar has vanished again."

Once more Nick switched off. The launch was now within fifty yards of the dam, but although her crew could see every detail of what was going on, they themselves were lying in the black shadow under the rocky rim of the lake. Yet in spite of the fact that it was not likely that any of the Night Folk could see them, Jeremy grew more anxious with every minute that passed. There was always the chance that Bastin might have posted sentinels along the lake shore, and if any of his people happened to glance over the edge of the bank they could not fail to see the launch.

Deep as the shadow was, there was sufficient reflection from the searchlight ray to show them up to any one who came sufficiently near.

Mort whispered to Jeremy. "Say, I'm all of a jump. I don't mind fighting, but this waiting is playing the Old Harry with my inside."

It was just what Jeremy had been fearing, and he touched Nick's arm. "I've a notion we shall have to make a push for it," he whispered. "Mort is crocking."

"I don't blame him," growled Nick. "I've got cold chills crawling up and down my spine. What about Jake?"

"He's still sitting tight," replied Jeremy. "Hasn't said a word since we started."

Mort broke in. "Say, ain't that Kasim?" he hissed, and pointed towards the dam.

"By gum, it is," said Nick as he stared at the brown, mask-like face which had suddenly appeared at the back of the dam. "Ugh, he gives me creeps."

"Never mind about that. Shove on," ordered Jeremy urgently.

Nick's right hand shot to the switch. He pushed it down. Nothing happened.

"What's the matter?" asked Jeremy.

"How do I know! The darned thing won't work."

"Can you put it right?"

"Got to find out what's wrong first," replied Nick, and Jeremy felt rather than heard the intense nervous strain under which his friend was labouring. Nick opened a small tool-box and for the next few minutes was desperately busy. Jeremy watched him in silence, for he himself could do nothing to help. His gifts lay in other directions.

Nick worked by the light of a tiny electric torch which he had hung from a hook well under the coaming of the hatch. And the others watched in aching suspense. At last Nick looked round, and in the dim light Jeremy saw his thin, keen face set like marble.

"The game's up, Jeremy," he said. "The wires are gone—bitten through by acid which has been carefully set to destroy them. It would be at least an hour's job to replace the wires even if we had spares. But I needn't tell you we haven't."

Jeremy drew a long breath. "So now we get to the bottom of Nartas' plot," he said softly. "Nick, what do we do?"

Before Nick could answer, someone else spoke. "We must go ashore and fight. It is, our only chance." The voice came from Jake, but it was not Jake's voice, and the other three turned and stared at the little black-faced figure in speechless amazement.

"Who are you?" Jeremy managed to get out.

"I—oh, Jeremy, do not be angry—I am Chalma. I—I had to come with you. I could not let you feel that no one of the people of Koom was willing to help you."

Jeremy was so paralysed that for the moment he could not find words. Chalma covered her blackened face with her small hands, and they heard her sob.

Then Jeremy spoke. "My dear, it was splendid of you," he said hoarsely. "But—but what in Heaven's name are we going to do now?"

Chalma drew herself up. "You are to do just what you would do if I were Jake," she said with dignity. "I came as a boy, and I am going to be a boy and help you all I can."

"I guess you got pluck enough for a whole bunch of boys," said Mort. He picked up an oar. "Say, Jeremy, shall I shove her ashore? There's a place where it looks as if we could land all right."

"A very excellent place to land," came a harsh voice from the bank, and a flood of light from a powerful acetylene lamp fell upon the boat, half-blinding its occupants.

Instinctively Nick reached for his pistol but the voice spoke again. "You are covered," said Bastin smoothly, "and, much as I should dislike to use violence, the first of you who attempts to shoot will die. That armour of yours, while it will, perhaps, protect you from sling stones, is utterly useless against nickel-pointed bullets from a modern pistol. See now. I will lift the light so that you may see for yourselves that resistance is useless."

He gave an order in strange, clucking words, the light was lifted, and there stood Bastin with a pistol in each hand, both levelled on the boat. Behind, and a little above, was Kasim, similarly armed, while higher still were a dozen at least of the repulsive Night Folk, all armed with slings.

"We're sure up against it," Mort muttered, and Jeremy realised that he spoke no more than the bare truth. And yet he hesitated. To yield themselves as prisoners without striking a blow was too bitter a business to bear thinking about.

Nick spoke. "It's no use, Jeremy," he whispered. "If it was just ourselves, I'd say shoot, and take chances. But we can't risk Chalma. Try and make terms."

"I am waiting," said Bastin from the bank.

"What do you want of us?" asked Jeremy in a voice he hardly knew as his own.

"You will first throw your weapons ashore, then follow them, and yield yourselves as prisoners," said Bastin in his hard, level voice.

"We might as well chuck ourselves into the lake at once," retorted Jeremy. "It would be a pleasanter end than to be handled by those savages of yours."

"The savages, as you call them, shall not touch any of you—that is, unless you resist," replied Bastin, "I give you my word on that."

"But what are you going to do with us?" demanded Jeremy.

Bastin's thin lips parted in a slight smile which made his long, yellowish face more sinister even than usual. "You are in no position either to ask questions or make terms," he said, speaking in cold, precise English. "Yet I have no objection to telling you that your lives are in no danger, and that I merely mean to hold you as hostages to obtain from Phra that which I desire."

It came to Jeremy that he knew exactly what secrets Bastin desired, and the awful uses to which he would put them. He still hesitated, and, had he and Nick and Mort been alone, he would have risked being shot down in a last effort to destroy this evil genius.

But they were not alone. There was Chalma to consider, and after a short pause he spoke again. "Very well," he said heavily, "I take your word on behalf of us all."

"You are wise," said Bastin, and there was just the ghost of a sneer in his level voice. "Now throw that pistol to me, then paddle the launch in close to the shore."

It was done, and a minute later the launch was alongside the rock shelf on which Bastin stood. "Oh, Jeremy, I am so sorry," said Chalma, in a broken-hearted whisper as Jeremy helped her out.

"Keep your heart up, little princess," replied Jeremy in an equally low voice. "So long as we are alive we won't despair."

"You will follow Kasim," Bastin ordered. "I shall walk behind you. Being white men, and having given me your word not to resist, I shall not tie you. But I should be only right in warning you that any attempt to escape will bring its own punishment."

Jeremy felt that the man must be inwardly burning with triumph, for the capture of Phra's daughter was surely beyond his wildest dreams. Yet not a sign of any such feeling was visible on his impassive face.

Not so with Kasim, whose evil eyes glowed with savage delight as they rested on Chalma. A renegade always hates worst his own people, and Kasim was no exception to the rule.

The man led the way up the rocks. The ascent was easy, and, in a few moments, all had reached the level summit. Kasim walked towards the dam. Chalma shrank back as he neared the hideous dwarfs who were still toiling on the great bar of granite, but Jeremy took her hand and she recovered her courage. Beyond the dam the slope ran upwards steeply among masses of the moss bush which covered so much of the ground in this underworld.

It was only as they crossed the path of the searchlight that Jeremy and the others realised its terrific power. The concentrated glare almost blinded them, but they had hardly crossed it before the great wireless sun lamps were once more shedding their steady radiance over the land.

Bastin gave a short bark of a laugh. "If I Phra is awake, he must have realised the situation," he said briefly.

And his words made Jeremy definitely sure that his suspicions had been correct, and that it was Nartas who had planned the whole business with Bastin.

There was some sort of comfort in the feeling that they were being watched from the Pyramid, and the renewed light was a great help in making their way up the steep and dangerous slope beyond the river.

"Where's the blighter taking us?" asked Nick in a whisper.

"Probably a cave," replied Jeremy in an equally low tone. "He's got to get us somewhere under cover, for the odds are that he knows the Koom people can see us so long as we are under the lights."

"It's a cave, sure thing," put in Mort. "There's the mouth of the darned place right opposite."

"It is a rest-house," whispered Chalma. "I have never seen one, but have heard of them from my father. There are many of them, but it is long since our people used them."

They passed in under an entrance similar to that of the tunnel by which they had first gained the under-land, only this had no gates. A short passage opened into a good-sized chamber with rooms opening off on either side. A cooking stove built of broad red bricks was against the wall, with a chimney above it in the rock, but the strange thing was that the furniture, all made of the indestructible grey metal, was still in position.

There were tables, couches, chairs, and stools, or rather, the skeletons of them, for the drapery had perished generations ago. Some attempt had been made by Bastin to clean the place, but it was still thick with the dust of ages. All this the prisoners saw by the light of a couple of rough lamps made Eskimo fashion, with a wick floating in a bowl of oil.

"Here are your quarters," said Bastin in his cold, dry voice. "The lady will have a room to herself and the others will share that one." He pointed as he spoke to one of the side rooms. "Now be good enough to sit down and listen to what I have to say."

The man's outward courtesy did not deceive Jeremy for a moment, for he had not travelled all the long distance from Cairo in Bastin's company without realising that he was one of the rare but terrible individuals who allow nothing to interfere with their ambitions, and in whom the ordinary human feelings are completely lacking.

They sat down and so did Bastin. Only Kasim remained standing near the entrance, evidently on guard.

Bastin spoke again. "My terms are these," he said. "I desire free access to the Pyramid of Koom and to all its secrets for a period of a week, or until I have made myself acquainted with its knowledge, including the electrical devices, the wireless lighting, and the composition of the grey metal. I specify also that I am to take away any manuscripts that I desire. I demand as well the hoard of pearls which are in the Treasury and which came from the pearl-mussel beds in the river."

He paused, but no one spoke. "I am to have an absolutely free hand, you will understand," he said, and though his voice was as dry as the rustle of dead leaves, an odd and dangerous gleam shone for an instant in his deep-set eyes. "One of you will take these terms to Phra. You can choose which of you is to go. Since the launch is useless he will have to make his way around the lake shore." He paused again. "I need hardly say," he added, "that the messenger will not be the Princess Chalma. She is too valuable an asset for me to part with until I have completed my negotiations with her father. Now I will leave you to make your choice, but it will be well not to be too long about it."

Jeremy struck in. "One moment, Mr. Bastin," he said coldly. "We are, of course, compelled to do as you desire, but I warn you that I think it highly unlikely that Phra will accede to your preposterous demands. Not one of us would recommend him to do so."

Bastin's eyes narrowed a trifle. "I do not think that Phra will be foolish enough to refuse—not while I have his daughter in my hands," he answered, and though his harsh voice was level as ever, the threat was deadly plain to all his listeners. "In your own interest also, Mr. Stretton, and those of Professor Durham, you will be wise to help rather than hinder me."

"Is Professor Durham still alive?" asked Jeremy curtly.

"He was when I last saw him. Some of his men who were foolish enough to resist me lost their lives, but he and Tuke were unharmed. If you help me I will help you to rejoin him—unless, of course, you are infatuated with the Lotus life of the Pyramid. You might be safer there than in the upper world, during the next few years," he added, with a queer twist of his lips.

Jeremy gazed straight at him. "There can be no bargaining between you and us," he said quietly. "And now, if you will be good enough to leave us, we will settle who is to go back to the Pyramid."

"As you like," said Bastin, and walked out of the cave.

Nick and Jeremy looked at one another, but it was Mort who spoke. "Say, couldn't the Princess and me change clothes, and she get back home? Then we wouldn't care a cuss what old Sour-face said or did. Ask her, Jeremy."

But Chalma herself knew enough English to understand. She shook her head. "Jeremy," she said, speaking in her own language, "Tell him that it is a brave thought, but that it is impossible. I am so much smaller than he that this Bastin would quickly see through the deception."

Jeremy shook his head ruefully. "She says it's no go, Mort, and I'm afraid she's right. I think that Nick had better take the trip."

"But he don't speak the language," objected Mort. "I guess it's up to you, Jeremy."

Nick cut in. "No. Someone's got to be here to keep up our end with the Bastin beast, and Jeremy's the only one who can do it. I'd better go. I can make Phra understand all right. Then I'll come straight back."

"You jolly well won't," retorted Jeremy. "You've got to stay and ginger up the crowd to rescue us. With your engineering knowledge and their scientific devices it's a pity if you can't dodge up something to snooker Bastin. Besides, what's the use of giving the fellow any more prisoners than he need have?"

Chalma had been listening eagerly, and though she did not understand all that was said she managed to get the general drift of it. "Yes, Nick should go," she told Jeremy. "And let him say to my father that he shall open the sluice gates of the pool and release Krah."

Jeremy stared. "Whatever for?" he asked.

"For two reasons, Jeremy. The home of Krah for generations was the lake, and it is in my mind that he will desire to return there."

"You mean that he will tackle the dam?" asked Jeremy rather breathlessly.

"I do not think that even the bar of granite would stop him," Chalma answered earnestly.

Jeremy swung round to the others. "Listen, you chaps," he said eagerly. "Chalma has struck a notion which may save the whole situation. She says that if Krah is let loose, he'll come down the creek into the river and up into the lake. If he does, Bastin may shoot till he's black in the face, but I don't think Krah could be stopped with anything short of a field gun."

"Gee, but that's hot stuff!" exclaimed Mort so loudly that Nick held up a warning hand. "Softly, Mort, we don't want Bastin to get wise to this notion. Anyhow, it's a top-hole scheme, and, if it works, ought to save the dam."

"Then you get right on with it, Nick," said Jeremy. "Tell 'em they'd better turn the lights out while they're at it, for we don't want Bastin to get on to Krah's arrival until he's on the spot."

Nick nodded. "I'll go. Shall I tell Bastin?"

"One moment, Nick," said Jeremy. "Watch out for Nartas. That beast has got some means of communicating with Bastin, and if he gets wind of the Krah game Bastin will have time to get his men out of the way. So be careful."

"I'll be careful, all right," said Nick, and the way in which his lean jaw set boded no good for the traitor.

Bastin was standing outside the cave, watching the savages on the dam. "I am taking your message," Nick said to him. "I presume you will stop work on the dam until you have Phra's reply."

"You expect too much, Mr. Prest. I have no intention of stopping my men. At the same time there will be no fear of my destroying the dam so long as Phra complies with my requests."

"I'm not fool enough to argue with you," said Nick bluntly. "But there is one thing I want before I start—my sword. Without it my chances of reaching the Pyramid are slim."

"You can have your sword," replied Bastin coolly. He called Kasim, and the renegade brought the weapon. But Nick noticed that Bastin as well as Kasim had their automatics ready in their hands.

"You are not taking any chances," Nick permitted himself to say, but the sneer was lost on Bastin.

"I never take needless chances," he answered drily. "And I do not ask you to. Here is your sword."

He paused, and fixed his queer, greenish eyes on Nick. "Of course, you have planned not to return," he said. "Ah, I was sure of it," as Nick started slightly. "But you will be good enough to remember that, if I have not my answer within six hours from now, I shall take certain steps, the first of which will be to remove all my prisoners to the Lower Level."

"Not the Princess!" exclaimed Nick sharply.

"All the prisoners, I said," Bastin answered. Nick's fingers tightened on his sword, but the muzzle of Bastin's pistol was within a foot of his stomach. He bit back his anger with a fierce effort. "You may expect an answer within the time specified," he snapped, and walked away.

Nick had not watched the Great Mirror so much or so often as Jeremy, but he had looked in it enough to be aware that this underworld was no place for a man to walk alone. Since the failure of the people of Koom to cultivate or police the land the monsters had steadily increased in numbers, so that now it was more perilous than the thickest and least known of Central African jungles.

Over and over again, when he had been standing before the Mirror in the Observatory, he had seen strange creatures slinking among the moss bushes or crouching in the cracks and crevices among the rocks. The watchers at the Mirror kept careful record of these beasts, and all of them were photographed and carefully classified in the great library of the Pyramid.

The distance around the lake from the dam to Koom was less than two miles, but the ground was badly broken by deep ravines and most of it thickly bushed, so Nick knew that it was up to him to keep his eyes open, and walk warily.

For all that, he had few thoughts to spare for the dangers surrounding him. He was too miserable. "I might have known that Nartas would do us down," he said to himself. "I ought to have looked at the engine of the launch before we started out. I'm the only one of the lot who knows a dam thing about it, and it's my fault we are in this filthy mess."

A snake writhed across his path, and he slashed at it, cutting it in two. Then all of a sudden he came to the edge of a ravine which ran inland from the lake. It was too wide to jump, and it looked to Nick as if he would have to walk a long way to get round the head of it. He turned to the left, hoping to find some place where the sides were not so steep, and, after a bit, did come to a spot where he thought that he could climb down to the bottom and up the other side.

He was in the act of swinging over when he caught sight of a pair of lambent green eyes glaring upwards through the darkness, and in one jump he was back on firm ground.

"Ugh, what a brute!" he gasped as he looked down again. The thing was a sort of frog. At least, it was frog-like in shape, but as big as a large bulldog, and covered with thorny spikes. Like so many of the underland animals its skin was faintly luminous, shining with a nasty blue glimmer. Its head was huge and its mouth nearly a foot across. It was not at the bottom of the rift, but seated on a shelf only about six feet down on the opposite wall of the cleft.

"Regular living nightmare!" said Nick. "I'll have to go round after all."

The words were hardly out of his mouth before there came a sharp call from the air above. It was the danger signal from the heights of the Pyramid, and in a flash Nick knew that the warning could not have anything to do with the frog-beast, for the watchers must have seen that he had already spotted that.

Something else was after him, and he turned like a flash to see what it was. Even as he did so, with a crash and a rumble, a great stone came thundering down the steep slope behind him, and Nick had barely time to leap to one side before it ripped across the very spot where he had been standing an instant before, and went plump into the ravine.

Nick was never one to run away from danger, but he was not fool enough to go charging up the hill, with the certainty of meeting another rock rolled by his unseen enemy. He flung himself down behind a boulder which was just big enough to hide him.

As he did so, there rose from the ravine a most horrible squawk, and with one mighty bound, the frog-beast came soaring out of the depths, alighting actually within Nick's reach, but, luckily for him, on the far side of his boulder.

At close quarters it looked even worse than before, for its great mouth was armed with yellow fangs like those of an alligator, and its skin was a livid white. Greenish blood dripped from a nasty gash in its side.

Nick grasped his sword, expecting that the thing would be on him next moment. But it did not see him and apparently could not smell, and, after a pause of only a second or two, it went straight up the slope in a series of tremendous hops. Before it reached the top the air was torn by a hideous scream, and out of a patch of moss bush a figure shot up and ran like a hare, with its loose tunic flying behind it. Nick caught the merest glimpse of the man's face convulsed with such terror it was hardly human, but that one glimpse was enough.

"Nartas!" he exclaimed, and, springing to his feet, ran up the slope as hard as he could pelt.

The frog-beast evidently meant business, and with its great leaps went up the slope much faster than Nick could run.

"Looks as if Nartas will get it this time," was the thought that flashed through Nick's mind as he ran. Yet when he got to the top, Nartas was still a couple of jumps ahead of his pursuer, and the speed at which he was racing across the rough ground was little short of a miracle.

But it could not last. The frog-beast was covering at least ten feet at each jump, and next moment it had caught the fugitive, and Nick saw it go for Nartas with its enormous jaws wide open. They closed with a clack that sounded like a cupboard door being slammed, and Nartas stopped with a jerk and a despairing yell.

Next instant, however, he was sprinting ahead again, and in spite of the seriousness of the situation, Nick almost laughed. For the frog had missed Nartas and merely got a mouthful of his tunic, and Nartas was dragging it along behind him with all its teeth tangled in the stuff.

No material ever made could stand the strain and, with a loud ripping sound, the tunic tore in two, and Nartas went ahead again, leaving the frog with a mouthful of drapery.

"This sees his finish," muttered Nick, running harder than ever. And just as he spoke Nartas tripped, went on his head into a clump of moss bush, and absolutely vanished from sight. The frog-thing took a jump which cleared the whole clump, then seeing nothing ahead, whirled round and started to force its way into the bush.

The bushes seemed to bother the beast. Indeed, they were tough as wire and the frog-thing had difficulty in forcing its huge head through them. All the same, it would have been all up with Nartas if Nick had not arrived when he did. The moment that the creature's bulging eyes fell on the new arrival it abandoned its efforts to reach Nartas, and, gathering itself, leaped straight at Nick.

So quick was it that all Nick could do was to use his sword like a bayonet to receive the charge. The frog's chest met the blade full, and the razor-like point sank into the great, gross body as into a cheese, but the weight of the charge sent Nick reeling backwards, and as the frog fell to the ground, his sword was wrenched from his grasp.

Left weaponless, Nick was helpless, and all he could do was to turn and bolt for safety. To his horror, the brute came after him, and he heard the heavy thud-thud of its leaps close behind him. Running blind, he suddenly saw a tall pile of rocks in front of him, and with a jump and a scramble went up them.

Gaining the summit, he snatched up a big stone and turned, prepared to sell his life as dearly as possible. He was just in time to see his hideous enemy come after him with a soaring leap. But big as the jump was, it was not enough to reach Nick's lofty perch. The creature landed on a narrow ledge a few feet beneath him and hung there clawing frantically for foothold, and making hoarse croaking noises.

Lifting the stone at arm's length above his head, Nick hurled it downwards with all his force, and with such good aim that it caught the frog cleanly between the eyes with a horrid squelching sound. Frog and stone went crashing together to the bottom of the rock pile, and there the nightmare thing lay flat on its back, its scaly green legs twitching in a death agony.

Nick wiped the big drops from his forehead as he watched it die. "A close call," he said hoarsely, and scrambling down, drew his sword from the still quivering body and went back to look for Nartas.

Nartas had managed to creep out of his moss bush, but that was all, and he lay on the bone-dry rock in little better case than the frog itself.

"Get up!" Nick ordered curtly. "Get up, you beast."

If Nartas did not understand this forcible English, he at any rate comprehended Nick's meaning, and made an effort to regain his feet. But the only result was that his legs folded under him like wet paper, and he dropped again. The man, you see, had never been out of the Pyramid in all his life before; he had never fought, never been in danger.

Nick, however, was in no mood to consider such things. All he knew was that Nartas had first betrayed him and his friends to Bastin, next tried to murder him, and ended by nearly getting him slain by the frog-thing. Just at this moment he was strongly minded to serve this human reptile as he had done the four-legged one, but he had a sort of idea that Nartas might be more useful alive than dead, so what he actually did was to give the wretched coward a sharp prick in the leg with the point of his sword.

This prescription acted like magic, and with an ear-splitting yell, Nartas bounded to his feet, and stood quivering all over, looking at Nick as a whipped cur looks at its master. "March!" growled Nick, pointing towards the Pyramid.

Then, before either he or his prisoner could make a step, out of the air above came the mighty voice of warning. "More beasts!" growled Nick. "'Pon my soul, I'm fed up."

But it was not the sort of beasts that he was expecting, for as he stared warily around he became aware that a party of the Night Folk, a dozen or more strong, were coming rapidly up from the south.

"This is your fault, you miserable hound," said Nick bitterly to Nartas. "You've roused the whole cavern with your infernal yelling."

And just then the voice came again and this time Nick caught the words. One was "Alga," which he knew meant lake. It was enough. He was to go towards the lake, and he ran, driving Nartas before him.

The distance was nothing, but the ground was very bad, and Nartas was not exactly in running trim. It took two or three minutes to reach the lake, then the first thing Nick saw was a launch coming rapidly from the direction of the Pyramid. He stared and rubbed his eyes, for the launch, a small one, had no one in her!

But his puzzlement lasted only a moment. "A crewless craft," he said aloud—"directed by wireless, of course." He gave Nartas a prod. "Get down there," he ordered.

Alone, Nick could have got down in a few moments, but Nartas delayed him, so that when they reached the little beach where the launch was waiting, their pursuers were on top of the cliffs behind them, and an instant later, sling stones began to whizz through the air. One struck Nick, but his armour saved him, and seizing the controls, he swung the little craft round.

A fresh shower of stone bullets sprayed the water all around them, and several clanged loudly against the metal of the boat, but, by a miracle, Nick and Nartas were still unhurt. Nick twisted the tiller, causing the boat to run in zig-zags so as to spoil the aim of the Night Men. Then, just as he was almost out of range, a metal-pointed spear flung from the heights to the left, came down in a great curve, and missing Nick by a matter of inches only, drove right through the thin bottom of the boat.

"That's done it," growled Nick. "Was ever such rotten luck?"

As soon as he was out of range he stopped the boat and tried to plug the hole. If the material of which the boat was built had been wood he might have succeeded, but the grey metal had opened in a jagged hole, and it did not take Nick more than a few seconds to realise that the job was hopeless.

"I'm certainly between the devil and the deep sea," he said aloud. "And this time there's no way out."


CHAPTER IV

"The devil and the deep sea." Yes, that was it exactly, but of the two Nick thought he preferred the land fiends to the sort that lived in the lake. He had his sword, and he could fight the Owl Folk, but once the launch sank and left him swimming, there was no fighting the dreadful denizens of the deep, dark lake.

He pushed over the tiller, and the little launch, though half- filled with the water that was spouting in steadily through the spear hole, responded and headed back for the shore. The savages saw and shouted—a hideous sound, more like the jabbering of apes than any human speech.

Nick's eyes scanned the beach, searching swiftly for any spot which would give him shelter from the stones and spears of his enemies, but he saw none. He headed for the far side of the tiny bay in which he and Nartas had embarked, hoping against hope that somewhere beyond he might find what he was looking for. Each moment the dainty little craft sank lower in the water, yet the engine still worked, and she drove forward.

The Owl Men saw Nick's plan and raced along the inner side of the bay, leaping from rock to rock as actively as monkeys.

"They know they've got me," groaned Nick. "They'll have me before I can get a footing on those rocks."

The point of rock at the far side of the inlet was high and steep and hid all sight of what was beyond, but Nick made up his mind to round it if the launch would float long enough. She did, and as she cleared it Nick gave a gasp of relief, for suddenly a little island showed up. "A chance still!" he said, and pushed the lever over as far as it would go, and gave her all the current the engine would take.

The island was barely a hundred yards away, but it was touch and go whether the launch would make it before she sank. Nick drove her desperately, and she was within a couple of lengths of the island when water reached the magneto and with a slight hiss the engine died.

Nick sprang up, seized Nartas and literally booted him over the bow into the water. It was only waist-deep, and as the terrified traitor struggled ashore, Nick made a flying leap after him, and both gained the little shingle beach in safety.

As Nick came ashore the first thing he saw was a creature resembling a great green snake which came gliding swiftly downwards from among the rocks. It was about eight feet long, with a body as thick as a man's thigh, a long, narrow head and wide jaws armed with sharp, white teeth. Screaming with terror, Nartas scrambled wildly up the rocks, but Nick, drawing his sword, slashed at the horror. The razor-like blade shore it clean in two, and as the severed parts writhed among the stones, Nick saw that it was no snake, but a monstrous eel.

"No end to 'em!" growled Nick, kicking aside the tail-end of the ugly thing, and at that moment Nartas started yelling again. "If another of those beasts has got him it can jolly well have him," snapped Nick, but all the same he went scrambling up over the rocks in the direction in which Nartas had gone. The rocks, bare for the most part, were covered here and there with a growth that looked like coarse twine. It was in bloom, the flower cups being each as large as a saucer and dull purple in colour. They resembled those of that fly eating bog plant called Sun-dew.

Next moment Nick caught sight of Nartas. He was on his back in a patch of this queer growth, and was screaming like a steam- engine with the valve wide open, and struggling desperately, yet it was quite clear that he was pinned to the rock. As Nick ran up he saw that the man was in the middle of a patch of this unpleasant-looking vegetation, and that some of the stringy stalks were twisted round his ankles. Others were writhing towards him, clutching at his wrists. It looked to Nick as if the plants were endowed with a sort of horrible life.

"This is the limit," he growled as he slackened his pace. The moment he came close, the leathery tentacles began to stretch and crawl towards him, but using his sword like a scythe, Nick mowed them down and got near enough to cut those that were holding Nartas. Then he dragged the man out of the quivering tangle and dumped him forcibly on a chunk of bare rock.

"Sit there!" he ordered, "and, by thunder, if you get into any more trouble you can jolly well get out of it yourself."

Nartas was quivering all over like a jelly, and his face the colour of cold ashes: But Nick had no pity to waste on him and made his way gingerly to the highest point of the island from which he could get a view of Koom. He wanted to see if they were sending another boat, for he took it the watchers had already seen what had happened to the last one.

To his great relief another launch was already on the way, but this was not crewless, for there was another person in it, and as it came swiftly across the mirror-like surface of the lake, Nick was able to see that the solitary occupant was small and black- faced. "Jake!" he exclaimed. "Thanks be, I'll have someone to talk to now. 'Pon my Sam, I should go dotty if I had to tackle any more of this bad-dream stuff on my own."

He waited till Jake was nearer, then beckoned him to come round to the landward side of the island and ran down to meet him. Jake beached the launch carefully and jumped ashore. "I'm shuah glad to see you, Marse Nick!" he cried. "Gee, but I thought dem dirty rascals had yo'."

"Don't mind telling you I thought so myself," said Nick. "They would have, too, if I hadn't spotted this island." He paused a moment. "I suppose they know in the Pyramid what has happened?"

"Dey knows," replied Jake gravely, "an' de big boss, he's mighty nigh crazy."

"Phra, you mean. Then he's awake?"

"Yas, sah, he's awake suah 'nuff, and up in de Watch Tower. Little missy, she didn't ought to have played dis trick."

"Perhaps not," said Nick, "but it's done and now it's up to us to get her out of it."

"I'se plumb ready, Marse Nick," answered Jake quietly. "I'se got a sword and two ob dem shooters. I reckon you and me kin fix dat Bastin."

Nick's heart warmed towards the plucky lad, and for a moment he felt a wild desire to take him at his word and make back for the dam. But, of course, he knew that any such attempt was sheer madness. "We have a better notion than that, Jake," he said. "The Princess put us up to it. We are going to turn Krah loose."

"Yo' be careful," whispered Jake swiftly. "Dat Nartas kin hear ef yo' speaks so loud." Nick swung round, and there, sure enough, Nartas was standing on the beach close behind them. He reviled himself for his carelessness; for, though Nartas knew no English, yet it was possible that he had caught the one word, Krah. But Nartas looked such a poor, shivering wretch that he took comfort.

The fellow did not seem capable of much more mischief, and, anyhow, once he was back in the Pyramid he would be taken good care of. "You're right, Jake," he said. "I was a fool to say what I did. But I'll tell you all about it when we get back. Meantime, the quicker we reach Koom the better. Bastin has given us six hours to accept his terms, and more than one has gone already, so nip in and let's get back."

"What you gwine to do wid dat ting?" asked Jake, pointing to Nartas. "He'd be mighty safe if yo' left him heah."

Nick hesitated. For a moment he was strongly tempted to accept Jake's suggestion, but then another thought struck him. "No, Jake. Bastin might come and collect him. We must take the beast with us." He turned to Nartas. "Get in!" he ordered, and a minute later he was steering the swift little boat back across the lake.

The outer water port opened to receive them, and when they shot in under the second arch in the central pool it seemed to Nick as though the whole population of the Pyramid was waiting around it. All the usual joyousness of these people was gone, and every face had a frightened, puzzled expression. They had lived sheltered lives for so many generations that this sudden disaster had upset them completely. To Nick they looked as a lot of children might who had suddenly been turned into the street, and his heart sank as he realised how completely useless they would be in any sort of trouble.

There was one exception. Phra, dressed in grey metal armour and standing on the landing-steps, was every inch a king, and Nick springing out of the launch bowed before him. Nick, although he had not Jeremy's advantage of knowing ancient Egyptian, had not been in Koom a month without picking up a good deal of the language. He could understand what was said to him, and made himself understood to some extent.

"My daughter?" were Phra's first words.

"Safe," Nick answered, "but a prisoner. I must speak to you in secret," he added. Phra nodded and signed to Nick to follow him, but Nick paused a moment. "Jake, see to Nartas," he said.

"Yo' bet I'll see to dat old rascal," was the answer, and Nick followed Phra along a marble-paved passage, through the mass of sweet-scented shrubs into a luxurious room.

"Now tell me," said Phra briefly, and Nick, making out with signs when words failed, told of how they had been trapped. Phra's fine face darkened as he heard of the treachery of Nartas. "He deserves death," he said, with a fierceness of which Nick had not believed him capable.

"True, Phra," he answered, "but Nartas' death will not help us now. For the present, let him be kept safely. What think you of the plan to release the Monster?"

"It is good," Phra answered promptly. "Krah will of a certainty move towards the lake, and if aught oppose him will kill."

"Then let us hasten," said Nick. "Time passes, and we have but four hours before Bastin carries out his threat."

Phra stepped to a sort of telephone and gave swift orders, then led the way out into the court again. Already the two priests who were the special guardians of Krah's pool were waiting, and with them a number of the little Robots. A sudden idea came to Nick, and he drew Phra aside.

"Will it be wiser to turn the lights out?" he asked. "Bastin must not know what we are about."

Phra considered a moment. "There is no need, my friend," he answered. "Having no mirror, that evil one cannot see what we are about. Nor do I think that his spies will dare approach closely to Koom. On the other hand, were the lights darkened his suspicions would be roused, and it might be that he would take precautions."

"It is like that you are right," agreed Nick. "And now I come to think of it, there is no need for any to leave the city, for, if I mistake not, the sluice gates of Krah's pool can be raised from within."

"Of a truth, that is so," said Phra, "yet may Krah refuse to leave his home. Therefore, must we take steps to drive him forth quickly, and for that purpose must visit the pool."

"I understand," Nick told him, yet inwardly he was wondering greatly what these puny Robots could do to shift such a monstrous beast as Krah.

Just then Jake came up. "Marse Nick, I done shut up dat Nartas."

"Where have you put him?"

"In one of dem strong rooms up in de top ob de town. And dat Nath, he tell me he'll look after him."

"That's good," said Nick. "You couldn't have got a better man. He's a bit old, but his head is screwed on tight enough. Our next job is to turn Krah loose."

"I reckon I better come wid yo'," said Jake shrewdly. "Ef dere's any ob dem debbil folk about we'll suah hab to fight 'em."

"Yes, you may just as well come," said Nick as he followed Phra to the door.

The door was the same through which they had gone out some days earlier to see Krah feed, and it gave Nick a nasty twinge when he remembered that on that occasion the little Princess had led them gaily. Jake saw Nick's lips tighten, and understood. "Don't yo' worry, Marse Nick," he said comfortingly. "We'll suah git dat Bastin."

Nick only nodded. A lump in his throat made it difficult to speak.

Outside the coast seemed clear, and nothing could be seen of any of the Owl Folk. Although these savages were constantly seen from the Watch Tower, moving up and down the river, yet they rarely travelled by land. It was probable, so Nath had said, that they were afraid of the strange beasts which, since the people of Koom retired to their city, had greatly increased in numbers and infested all the Under-lands.

For all that, Nick and Jake kept a very sharp look-out, for there was always the chance that Bastin might have sent out spies to follow Nick back to the Pyramid. It was clear that Bastin had managed to get some sort of hold over these savages of the Under- lands, though how he had done it was beyond Nick to understand.

The party consisted of five, Phra, Nick, Jake, and the two keepers. There followed half a dozen of the strange little Robots, who walked like wound-up dolls, and whose faces showed no sign of fear, surprise, or any other emotion. By this time Nick had got pretty well accustomed to them, yet he never looked at one without a queer wonder as to whether they were human beings or not.

Walking quickly, it was only a few minutes before the party reached the edge of the pool and stood looking down upon its dark, still depths. Phra turned towards the Pyramid and raised his hand, and as he did so the great, grey metal sluices began to rise. So perfect was the mechanism that not the slightest sound disturbed the stillness of the underground world. Only as they rose the water began to gush out and the dead, canal-like stream below the lock took life and movement. Higher and higher the great gates rose, and above them in the pool wide swirls and eddies appeared. But still there was no sign of the monster or his mate. A broad stream filled the conduit and the water murmured softly as it rose against the rocky sides.

The level of the pool itself began to fall slightly, then suddenly towards the upper end of the reservoir the water commenced to boil.

"He's a-coming," said Jake under his breath, and as he spoke the surface broke and Krah's vast head rose slowly into sight.

Nick drew a quick breath. Although this was not the first time that he had set eyes upon the Thunder Lizard, yet the gigantic size of the creature thrilled him even more deeply than on the previous occasion. This was a monster too tremendous and terrible for human understanding, a thing that belonged to the world's early ages. It seemed too much to ask one's eyes to believe that such a creature could still exist and have its being in this twentieth century. It wallowed to the surface until not only its terrible head showed, but also the great, spiked frill that ran along its endless length of back. Then slowly it began to swim towards the gates, and Nick saw that the two priests were actually shivering, while he himself had a queer feeling at the pit of his stomach.

But Phra remained unmoved, and again turned towards the Pyramid and raised his hand. Now the gates themselves began to slide back into deep sockets cut in the living rock, and the water roared and foamed in the rock-rimmed trench.

"He's a-gwine out," muttered Jake, but no one listened. And just then the water boiled again, and Krah's mate came swiftly up out of the black depths. Smaller than Krah, she was yet sufficiently terrible. As if she knew that something unusual was afoot, she shot forwards towards her mate with a swiftness that sent a three-foot wave surging and splashing against the sides of the pool. Krah stopped short.

Phra spoke to the keepers, and they in turn addressed the Robots. "They're going to drive him out," said Nick to Jake.

"Foh de land's sake, how dey do dat?" questioned Jake in amazement. "Why, yo' couldn't push Krah wid a ten-ton lorry."

"They've got some dodge," said Nick. "Watch!"

The Robots opened a metal case which they had carried with them, and taking from it a number of small, shining balls handed them to the keepers. The keepers flung these balls into the water behind the two monsters, and as each struck the water it burst into small pieces which went darting across the surface, hissing violently and flinging out a brilliant blue flame.

"Dey's duppy men," said Jake shaking his head. "Everywheres else but here water puts out fire."

"It's some preparation of sodium," Nick told him, but Jake was not convinced. To him the whole business was magic.

Magic or not, it had a speedy effect upon Krah, for as the flaring pellets bore down upon him he lashed out with his monstrous tail, sending foam flying high into the air, then suddenly darted towards the gates. His mate followed, and in a flash they were both through and out in the strong stream which was running down the cutting towards the river.

Instantly the gates began to close, but before they were quite shut, a signal from Phra stopped the unseen mechanism. "That's to leave them enough water to swim in," Nick said to Jake.

"I only hopes dey don't get stuck," said Jake. "It's a mighty narrow place for dem monstrous great beasts."

"They came up, so I expect they can get down," Nick told him. "And now we had best lose no time getting back to the Pyramid, for I want to be at the dam before Krah reaches it."

"Yo' mean in de power boat?" said Jake.

"That's it. We must manage to be on the spot just at the right minute, for no one can say what Bastin will do if he sees his plans smashed up."

"I spects he'll be plumb crazy," remarked Jake, but Nick had left him and was talking eagerly to Phra.

Somehow he managed to make him understand, and they all hurried back towards the Pyramid. Within the great, beautiful, scented hall the people stood still, like frightened sheep. By this time all knew the danger that threatened, but hardly one of them had the least idea of how to meet it. Phra at once gave orders for the best of the power boats to be made ready. "I will accompany thee and the dark-faced boy," he told Nick.

But Nick was strongly against this. "It will not do, sir," he said firmly. "There is no saying whether our plan will work or not. Suppose that it goes wrong, and that, instead of our capturing Bastin, he takes or kills us, then your people here are left without a leader. You yourself know how helpless they would be in such a case. I beg of you to stay. It is your duty to do so."

Phra frowned. "I do not need that a boy young enough to be my son should teach me my duty," he answered harshly. "My daughter is in danger, and it is I who must help her."

"You are wrong," retorted Nick bluntly. "Two of us are better than three in a business of this kind, and you can do more to help your daughter by staying here than by risking your life with us."

Phra stiffened and his eyes flashed angrily. For some moments he stood glaring down at Nick, but Nick faced him steadily, and in the end it was Phra who yielded. "Yes," he said, with something like a groan. "My inner voice tells me that thou art right. I know, too, that thou wilt do all that can be done, but how I shall endure the waiting—that I cannot tell."

"We, at any rate, must not wait," Nick told him. "We must be near to the dam at the moment when Krah approaches. And listen, Phra, at that moment the great lights must be extinguished so that Bastin shall not know of our approach."

"It shall be done. I will direct the engineers myself. But if matters go awry and this Bastin gets the upper hand, what then?"

Nick shrugged. "In such a case it is useless to plan ahead," he answered. "But this I promise you, so long as life remains in me, so long will I follow Bastin to save your daughter and my friends or to exact vengeance." He flushed as he spoke. "I'm talking drivel," he said to himself, "but, all the same, I jolly well mean it."

Phra seemed to read his thoughts. "I trust thee," he said. "And now the boat is ready."

"This time I am going to look it over myself," said Nick in English. "I can't afford to take any more chances."

One of the engineers was busy in the launch. He was a man named Shem, whom Nick had met in the great engine-rooms beneath the Pyramid, and knew and liked. "How long will this engine run?" he asked.

"See'st thou these cases? Each containeth a power for six hours, and there are twelve of them. Thou dost place them thus, and by making these metal bands meet—"

Nick cut him short. "Storage batteries. Yes, I understand. And now I want lights and food."

"The slaves shall attend to the food. For lights I have already provided. There are here two lamps stored with the earth force and of great power."

"Good!" said Nick. "And weapons—I want a couple more of the crossbows."

"They shall be sent for," Shem told him. "And see—here at thy hand are certain small globes, each of which being broken sendeth out a dark and deadly vapour. It may be they will be of use in the battle with thine enemies."

"Smoke bombs!" exclaimed Nick. "A top-hole idea, Shem!"

Shem smiled, for though he did not, of course, understand the English words, he realised that Nick was pleased. And he, like his fellows who did all the really difficult work of Koom, liked and admired the white boy who was so deeply interested in all their wonderful machinery.

The crossbows were brought, and with them two fresh swords. Also food and drink was stored in a locker under the stern. Nick saw to everything himself, and with Shem's able help, all was soon ready. Nick stopped a moment to say good-bye to Phra, and at that moment one of the little Robots came silently through the throng and gave Phra a slip of parchment. Phra glanced at the writing, and his face cleared a little. "Krah hath reached the river," he told Nick, "and the watchers say he turneth towards the lake."

"It is good news," said Nick simply. "And now farewell, Phra."

"Farewell, my son," Phra answered. "And the gods be good to thee, for I think that upon thee hangeth the fate of this great city. But this remember. Should matters go ill, as may happen, no sacrifice is too great to save my daughter and thy friends from the dread terrors of the Outlands. Rather would I give to this Bastin all that I have than that a hair of their heads should be hurt. Thou wilt remember this, my friend."

"I will remember," Nick answered, but made no other promise. "Not much," he said grimly to himself. "Not even for Jeremy and Chalma's sake will I chance Bastin getting inside these walls. With the knowledge he could gain here he would wreck the whole world." He stepped into the launch and Jake followed. Men pushed over a small lever and the launch began to move.

"Farewell!" the people called. "The gods be good to thee." But the voices were low and soft, for all had been warned not to make any great shouting.

The launch glided silently through the open water gate, and as she passed out the guard on the doors saluted. The little craft quickened as she ran down the short channel leading into the lake, but before she reached the lake itself, Nick spoke to Jake. "Jake, you must not be seen," he said. "If Bastin or his spies spot you they may smell a rat. Get down into the bottom of the boat, and don't move until I tell you."

Jake nodded and obeyed, and to anyone who was watching it would seem that Nick was the only occupant of the power boat as it sped across the broad lake.

Nick kept as close to the shore as he dared, for above all things he was anxious that Bastin should know nothing of his approach until he was quite close to the dam. So long as he could keep out of sight he had little fear of being heard, for the boat itself was so built that it glided through the water as silently as a bird swimming. True, it made a slight wave, but the lake, although no wind ever stirred its surface, was constantly starred and rippled by the movements of the fish and monsters which dwelt within its depths.

The chief risk in keeping so close to the shore was from savages hidden among the crevices of the rocks, who might hurl their spears into the boat, but Nick watched carefully and at the slightest sign of movement among the strange growths on the bank steered away to a safer distance. He saw none of the Owl Folk, and no beast attacked them either from the land or water. Yet the strain was very heavy, and he longed for the moment when action would be possible.

As he passed the little island where he had taken refuge some hours earlier, the sound of hammers came faintly to his ears.

"They're still at work on the dam," he said to Jake in a whisper.

"Den dey ain't seen Krah yet," answered the other.

"Not yet," agreed Nick. "I only wish I knew where the beggar was, Jake."

"Dey can see from de Watch Tower. Won't dey tell us?"

"No, I specially asked them not to use the Mighty Voice for fear of warning Bastin. The only warning we shall get is when the great lights go out."

Jake nodded. "Den we'se jest got to go as close as we dares and wait. Dat's all, Marse Nick."

"That's all, as you justly remark, Jake," replied Nick dryly, "but if we go too close Bastin will spot us, and if we are too far away then we miss our chance of nipping in at the right moment."

"I reckon we better be too far than too near," said Jake sagely. "It won't nebber do for dat Bastin to see us, but dis hyah boat can move mighty quick when she's got full power. I guess yo' better push her into one ob dese hyah little creeks a piece farther on, and wait."

"That seems sound," allowed Nick as he steered close under the point of rock beyond the island. The nearest of the great lights was a long way to the right, so fortunately the shadow was deep under the cliffs which bordered the lake.

Bit by bit Nick edged onwards, and all the time the ring of the drills on the dam grew clearer. At last he gained a tiny bay something less than a mile from the dam, and nosing the launch into it, shut off power and floated silently. "We can do the rest of the distance in little more than two minutes," he whispered to Jake. The words were hardly out of his mouth before black darkness fell like a pall upon the whole underground country, darkness that was almost instantly cloven by the blinding beam of the great searchlight.

The change from light to darkness was so sudden that Nick felt as if he had been blinded, and for a moment his fingers fumbled aimlessly for the controls. But only for a moment; then the little launch shot out of the bay, and, turning to the right, went racing for the dam under full speed. The searchlight blazing over-head gave Nick his direction, but its ray, instead of being directed as before upon the dam itself, was now raised high above it, painting a circle of glowing radiance upon the soaring cliffs which supported the roof of the cavern.

"Krah's a-coming! He's suah coming," chanted Jake in wild excitement.

"Shut up, you idiot!" snapped Nick. "Shut up and get your crossbow ready!"

A wave heaped itself behind the launch, hanging like a white and faintly luminous wall at her stern. She was going all out, and her pace was even beyond what Nick had hoped for. The risk was frightful, for Nick could see nothing of the dam, and if he hit it or the rocks at this pace the little boat would be flattened like a tin can. The searchlight, however, was being lowered, and he could see the great white circle sweeping downwards across the face of the cave wall. He trusted that it would show him the dam before he reached it.

The sound of the drills had ceased, but had been succeeded by a jabbering like that of a pack of excited baboons. "Krah hasn't reached them yet, or they'd be singing a different song," muttered Nick, as he strained his eyes through the gloom towards the dam. He licked his lips, for excitement had dried his throat and mouth so that he could hardly breathe.

The ray still swept downwards; it shone upon the broken ledges near the foot of the wall, and Nick had a glimpse of the black mouth of the cave where Jeremy and the others were imprisoned. The platform outside was bare, and Nick felt a surge of hope. If Bastin were on the dam then he, too, would be smashed by the monster and all would be well.

Another few seconds and the light would show the dam, but before this happened suddenly out of the stillness above came the thundering of the Mighty Voice. What it said Nick could not tell, yet one word he heard distinctly, and that word was "KRAH."

Jake caught it, too. "Dey's warning dem," he gasped. "Oh, my golly, dat Nartas, he've got loose, and he'd done warned Bastin."

"Impossible!" snapped Nick.

"It am true," insisted Jake. "Yo' watch!" He pointed as he spoke, and suddenly in the intense radiance of the light beam two figures ran furiously upwards. "Bastin and Kasim!" groaned Nick in horror.

"Watch out. Yo'll be on de dam!" cried Jake sharply, then, as Nick instinctively switched off, there came from the dam such shrieks and screams as seemed to split the very roof, and sent hideous echoes pealing for miles through the vast stretches of this underworld.

"Krah! Dat's Krah!" cried Jake. In the blinding brilliance of the light ray a vast head had risen suddenly from behind the dam. Krah it was, and a very angry Krah, for both the dam itself and the people upon it seemed to annoy him equally. With a movement amazingly swift for so vast a creature, he drew his head back, then, with the speed of a striking snake, he drove it forward right into the thick of the mob huddled helplessly upon the smooth surface of the great bar of masonry.

For the moment Nick forgot everything else in the sheer horror of the scene. "Fo' de Lard's sake!" he heard Jake gasp. "It's like beating flies off'n a window pane." No words could have expressed it more accurately. One moment the white stone had been black with bat-eared savages, the next it was bare except for some dreadful red splashes. A few survivors were scrambling madly up the steep slopes on either side, but the bulk of Bastin's workers had been literally wiped out of existence.

"Watch out!" Jake shouted. "Watch out, Marse Nick! He's a- comin' ober." Nick switched on the power again and sent the launch darting round in a swift circle. And as he did so Krah's whole monstrous body heaved forward on to the dam, and his front legs, each the thickness of a man's body, pawed and slithered on the masonry.

"He'll break de whole wall down," said Jake hoarsely, and for a moment Nick was convinced that he was right. It did not seem that anything made by man could withstand the colossal weight of the struggling monster. But those pyramid makers had built the dam so that it was firm as the rock in which it was set, and even Krah's struggles had no more effect than to dislodge a few blocks from the upper tiers of masonry. He reached the top, and for a moment his incredible hugeness blocked the whole gorge, then he had forced himself right over.

It was like a mountain being flung into the lake. Spray rose fifty feet into the air, drenching the surrounding shores, and a great wave went racing outwards. Quick as thought Nick turned the launch bow on to it, and she leaped high upon the crest. For a moment Nick held his breath, thinking she would swamp, but she settled light as a bubble, and lay swaying in the swinging eddies.

"He's gone!" cried Jake in breathless relief, but Nick was already heading back for the shore. The light still lay full upon the dam, but left all dark beyond.

The moment the launch entered the lighted circle pistol shots crackled out of the shadows high to the left and bullets came ripping past Nick's head. One struck the metal bows of the launch with a resounding clang, and another missed Nick so narrowly that he felt the wind of it upon his cheek.

"Get down, Jake!" he shouted, for the coloured boy, with utter disregard for danger, was swiftly fitting a steel bolt into his crossbow. "Get down, you idiot!" Before another shot could be fired the searchlight shifted again. It rose, leaving the launch and dam in darkness, and swept upwards towards the cave mouth. "Dere's Bastin!" cried Jake. "No, it ain't, it's Kasim. Hold on, Marse Nick! Let me jest hab one shot at him."

"I can't stop," Nick snapped back. "There's no time. That beast Bastin is getting the others away while Kasim holds us off."

"All de more reason for shooting ob him," urged Jake, and as he spoke he stood up and loosed off.

But the launch was travelling far too fast for accurate aim, and Jake's bolt failed to touch the sinister figure that stood high on a rock terrace, in the great glare of the giant light.

Nick swung the launch in under the dam and leaped out. "Hold her, Jake!" he cried. "I've got to see what's happening."

"Yo' can't see nothing," Jake told him, and next instant Nick realised that this was true, for the ray of the searchlight passing high above the gorge left the bed of the river in black shadow.

"A lamp! Give me one of the lights!" he exclaimed, and Jake wasted no time in getting one of Shem's electric lights out of the stern locker. "Hurry!" he hissed. "Dat Kasim, he's done gone."

But even when he had the lamp Nick could not at first find the switch, and he fumbled in the darkness, not daring to strike a match, for fear of bringing a fresh storm of bullets.

At last he got the hang of it, and a ray of amazing power flashed out. Concentrated by some peculiar form of lens, it flung a narrow beam which stabbed the darkness like a sword of white fire. At first it showed him nothing but the deep current of the river, running slowly and heavily between its rock-ribbed banks, but as he raised it the ray fell upon a large canoe which, paddled by half a dozen of the hideous Owl Men, drove rapidly down the stream. In the stern sat Bastin steering, and in the bow was Kasim standing, pistol in hand, while in the bottom of the boat lay Jeremy, Mort and Chalma. Jeremy and Mort were tied hand and foot, and evidently perfectly helpless. Only Chalma was free.

The moment the ray fell upon the boat Kasim raised his pistol, and at the same instant Chalma's bell-like voice rang out in warning. Nick had no time to switch out the light. Instead, he simply flung himself down on the top of the dam, and Kasim's nickle-tipped bullet tore through the air barely a couple of feet above his head.

"Nick!" came Jeremy's anxious voice out of the darkness. "Nick, are you all right?"

"I'm all right," shouted back Nick, as he switched off the light and rapidly crept away to one side. "What about you?"

Out of the gloom came the sound of a struggle. It lasted but a second or two; then it was not Jeremy's but Bastin's voice which replied. "And we, too, are perfectly safe," came the words in a tone of bitter irony. "You can go back to Phra, Mr. Nicholas Prest, give him my compliments, and tell him that his clumsy plot has failed. True, I have lost a few of my savages, but there are plenty more where they came from, and where I am now going. Tell him that, within an hour or two, his daughter and your friends will be prisoned in the Outlands, and that there they will remain until he accedes to my terms. Tell him that a white flag set here upon the dam will be the signal that he agrees to my terms, and that the sooner it is placed there the better for his daughter."

"Tell my father never to yield to threats," came Chalma's clear voice. "Tell him—" Then she stopped short, and Nick writhed with rage and misery at his inability to smash the brute who, plainly, had clapped his hand across the brave little lady's mouth.

Bastin spoke again. "You have my terms. It will be better for you and all concerned to accept them swiftly. I give you twenty- four hours, and if, at the end of that time, the flag is not upon the dam, I shall take further steps. Food is scarce in the place to which I am going. The prisoner's rations, slim at best, will be reduced from day to day, until Phra yields to my demands."

At this beastly threat Nick, for almost the first time in his life, lost all control of himself. Switching on his light again, he jumped off the dam on to the rocks to the right, scrambled up them, and set to running furiously down the river bank.

"Marse Nick—! Marse Nick!" cried Jake desperately, and scrambling out of the boat on to the dam, followed the other. Two spits of red flame darted from the direction of the boat, two pistol shots sent the echoes crackling and beating through the heavy air, and Jake saw Nick pitch forward and fall with stunning force.

When Jake reached Nick he found him lying on his face in a little hollow under a clump of moss bush. The lamp, which Nick had dropped in his fall, had been pitched straight into these bushes and was caught there, still alight. "Nick—Marse Nick!" panted poor Jake as he flung himself down beside the other.

But Nick did not move or answer, and Jake broke down and sobbed. "Dey's killed him. Dem debbils hab killed him," he groaned. "Oh, Jiminy, what will I do now?"

Jake was not the sort to give way for very long. "I'se got to get 'im back to the glass city," he said slowly, and hoisted him on to his back. Then, picking up the lamp, he went staggering slowly back towards the dam.

Jake was small, so that although Nick was slight and spare it was all the negro boy could do to carry him the short distance to the launch, and by the time he got him there and had laid him in the bottom he was quite spent. But there was work to do, and Jake was not going to shirk it. Somehow he had to get himself and the boat and Nick's body back to Koom. He opened the locker, took out a metal flask, poured a little of the greenish clear fluid into a mug, and drank it. This drink, called "Kal," was one of the many inventions of the people of the Pyramid, and was a restorative more powerful than any known in the upper world.

Almost at once Jake felt the aching fatigue pass, and was able to breathe easily again. He turned to Nick and set himself to find out where the wound was, and whether there was any life left in him. He had not far to look, for blood was running down through Nick's thick dark hair and staining his face an ugly crimson. "Shot right through de head," he groaned; then, dipping a handkerchief into the lake, began to wipe the blood away so as to find the wound.

"Steady on, you ass! What do you think you're doing with my face?" observed Nick, and as Jake stared at him in blank surprise Nick suddenly sat up and returned his gaze. "Ain't yo' dead?" got out Jake at last.

"Dead, you idiot! What made you think that?"

"Why, dat Kasim, he shot yo' plumb through de head. Dere's de blood a-runnin' out ob de hole right now."

Nick raised his hand to his head, and brought it away stained with blood. He looked at his fingers in a puzzled way. "I do seem to have got a bit damaged," he said slowly, "but I don't believe the blighter hit me. I tripped just as he fired, and whacked my head against something as I fell. But how did I get here?"

"I done carried yo,'" said Jake simply.

"You carried me," repeated Nick. "For the love of Mike, how did you do it?" Then he saw Jake's lips quivering. "Gad, you're white, Jake!" he added warmly. "But don't get the wind up. I'm really all right. A bit of plaster and I shall be as good as new."

Jake gripped the flask and poured out a stiff dose of the green fluid. "Yo' take dis, Marse Nick. It's a heap better'n plaster."

Nick swallowed the draught, and almost at once the dazed look passed from his face. "You're right, Jake. That's as good as a night's sleep. It's cleared my head like magic." He paused and drew a long breath. "So Bastin has got away?" he said grimly.

"Yas, Marse Nick. He's sure gone, an' Marse Jeremy and Mort an' de little lady wid him. It was dat dere Nartas pulled de trick against us."

Nick nodded. "Yes, I expect you are right. I remember it all now, and more particularly what that beast Bastin said about taking them to the Outlands and starving them till we give in."

"I guess dere ain't nothin' else for it but to gib in," said Jake sadly. "We can't leave de little lady to go hungry."

Nick's young face hardened, and it struck Jake he looked years older than he had an hour earlier. "We are not going to give in," he answered very quietly.

Jake's eyes widened. "What yo' mean, Marse Nick?" he asked. "It don't seem to me dere's anything to do!"

"Jeremy would never forgive us if we gave in," Nick told him. "I don't think the Princess would, either. Jake, it's up to you and me to handle this business."

Jake gazed at the other open-eyed. Then, as he saw the fierce resolve on Nick's face, he nodded. "I'se game to try, boss," he answered. "But I don't know what we kin do."

"I'll tell you what we can do, Jake. We will chase them down into these Outlands, or whatever they call the infernal place. Yes, I know there are two of us, but there are only two of them—two that count, at any rate. What's more, they won't be expecting us. Jake, it's them or us."

"I sure hopes it'll be us, Marse Nick, but dere's one ting it seems to me, you've clean forgot. We'se in de lake and dey's in de ribber. How yo' reckon to get dis hyah launch ober dat dam?"

"There are rollers—were, anyhow, unless Krah has smashed them. The launch isn't heavy. You and I between us can shove her over. Come on. Let's get to it."

He leaped out upon the dam as lightly as though he was fresh out of bed instead of having been hard at work for many hours on end, and hurried to the rollers, which were on the far side of the dam.

"They're all right," he said. "Seemingly, Krah didn't touch the rollers. Push the launch over the side, Jake."

As Nick had said, the launch was marvellously light. The grey metal, that was much stronger than steel and with similar magnetic properties, was quite as light as aluminium. Even so, it was a terrible task for two boys, neither of them big or heavy, to get her up the slope out of the water, and when at last they had succeeded they were both dripping with perspiration and limp as rags. Even then the job was not finished, for they had to lower her down into the river below.

Luckily there was a coil of stout rope in her stores, and here Nick's engineering knowledge came in. Using one of the rollers as a pulley, he rigged a double-purchase tackle, and presently the dainty launch was floating safely on the river side of the dam.

But all this had taken a deal of time, and Nick glanced uneasily at his wrist watch. "They've sure got a big start," said Jake. "Do yo' reckon we can catch dem, Marse Nick?"

Nick glanced down the immense length of the cave to where the last of the great lights cast its soft radiance on the face of a soaring cliff. "I can't say, Jake. They'll have shifted along pretty quickly with the stream, but, of course, we can travel three miles to their one."

At that moment the Great Voice began to thunder overhead.

"Can't make much of it," said Nick, as the booming sound died away, "but so far as I can judge, they're merely ordering us to return to the Pyramid."

"You ain't a-goin', Marse Nick?"

"Is it likely?" said Nick dryly.

Almost at once the voice came again, louder, more threatening, and this time Nick heard the words plainly. "Someone's getting cross," he remarked with a twisted smile.

"What did he say, Marse Nick?"

"Told us to come back at once—that if we didn't they'd turn the lights out."

"Who said dat?"

"I haven't a notion, but I don't believe it was Phra. Jake, they can see us. Get up and shake your head, and tell 'em to go to blazes."

Jake's pantomime left nothing to the imagination, and in spite of his bitter anxiety, Nick smiled slightly as he watched the boy. Next minute out went the great lights, but all that Nick did was to switch on his projector, and guided by its powerful beam, drive forward even faster than before.

Realising evidently that they were powerless to stop the pair from sticking to the chase, those in command in Koom turned on the current afresh, and the great wireless suns glowed out once more, flinging their soft radiance over the dark current of the river and the strange vegetation growing upon its rugged banks.

Here the river was deeper and less broken with rocks and rapids than the upper reaches, and Nick had no difficulty in keeping up a fair rate of speed. But curve after curve was taken, and still there was no sign of the chase.

Nick spoke at last. "Jake, I'm wondering if Bastin is trying to trick us. Suppose he's gone ashore somewhere and hidden the boat?"

"Dat's foolishness," replied Jake bluntly. "How'd Bastin know that we was following?"

"No, I suppose he can't suspect that," said Nick, "but we are getting near the end of the cave."

Jake glanced at the great wall ahead, towering endlessly upwards. "I guess dere's a hole somewheres for de ribber to run through," he remarked.

"A hole that leads to the Outlands," added Nick. "Yes, I've seen that from the Watch Tower, but even the watchers could not tell me anything more. They were scared green when I tried to get 'em to talk about it."

Jake shivered. "I reckon it's shuah a bad place," he said unhappily. Just then the launch rounded the last bend, and Nick pointed. "We shall know all about it pretty soon, anyhow, for there's the entrance," he said.

Dead ahead, and only a few hundred yards away, a great arch opened in the cliff face, and into it, with a low, roaring sound, the river poured, and so passed into the unknown.


CHAPTER V

There was awe in Jake's eyes as he stared at the black arch in front. "Is dat where dat Bastin hab gone?" he asked.

"Must have," replied Nick briefly. "There's nowhere else where he could have gone."

Jake screwed up his eyes in a way he had when puzzled. "But I done thought all de ways in and out ob dis place were fixed up wid gates, Marse Nick. Yo' 'member de job we haf to get in. How come dere ain't no gates hyah?"

"There have been gates," Nick answered. "See, here are the cuts in the rocks where they were fixed. Either Bastin or the Owl Folk have got rid of them."

Jake nodded. "Dat's so," he said, then added suddenly: "It's sure gwine to be mighty dark down in dat hole dere, Marse Nick."

"Dark enough, I've no doubt," said Nick, "but luckily we've got lights."

"Yo' tink it safe to use dem."

"Don't know whether it's safe or not, but, anyhow, we've got to. We can't risk smashing the launch against the rocks, and by the sound of it there's a pretty heavy stream through the tunnel."

As he spoke, the launch reached the great rock portal. Nick glanced back, and had one last glimpse of the upper part of the great Pyramid shining with soft and many-coloured light. "I wonder if I shall ever see it again," was his unspoken thought, then the launch slid swiftly into the gloom.

At once Nick pulled down the switch of the big head light and instantly a powerful beam glowed out and shone upon the curling eddies of the penned river and the smooth, dark rock which hemmed it in. The current was strong, but there was nothing like the fall which, from the roar, Nick had fully expected. The noise was caused by the stream striking against the walls and the sound echoing back from the rock arch overhead. The tunnel seemed fairly straight and the river itself was deep and smooth. Keeping just enough power to give steerage way, Nick held the launch in the centre of the stream and she travelled down it at a great pace.

"Keep your eyes skinned," Nick ordered Jake. "Watch out for any light ahead. I want to switch off before we get to the other end. It won't do to advertise our arrival in the Outlands if we can possibly avoid it."

"I get yo' boss," Jake answered, "but 'cording to what dem Koom folk told me, dere ain't a lot of light in dem Outlands."

"If you ask me, I don't believe that anyone in Koom knows much about it," said Nick briefly. "Still, there must be light of some sort, or even the Bat Folk couldn't live there."

Suddenly Jake touched Nick's arm. "Switch off, boss," he said in a low, quick voice.

Nick did so, and for a moment the sudden change left him with an unpleasant blinded feeling.

"I can't see anything," he growled.

"But I can, boss. Dere. Straight ahead. Jest a sort of blue shining."

"Yes—yes, by gum, you're right, Jake. I see it now." There was silence for some moments while the boat glided swiftly towards a semicircular patch of bluish light. This grew in size and strength, and within a couple of minutes the launch had reached the outfall and was once more in an open river. Open, that is, so far as its occupants could see, but that was not very far, for the light was thin, flickering, and uncertain, and a very different matter from the beautiful steady glow of the great wireless suns which illuminated the upper cave.

Just ahead a small point of rock jutted out from the high bank of the gloomy river. Nick checked the launch, and letting her drift toward the point, caught it with a boathook and stopped the launch's way. "We've got to have a look round before we go any farther," he said in a low voice. "We must try to get some idea of the lie of the land and conditions generally, for we don't know what we shall be running our heads against if we drive on blindly."

Jake looked round, and Nick saw him shiver. He did not blame the lad, for he himself was none too happy. "Buck up, Jake," he said quietly.

"I'll try, Marse Nick," Jake answered, "but I suah don't like dis place. Watch dem big shadows go jumpin', and what's dat nasty whistlin' dat comes ebery now and den?"

"I can't tell any more than you, Jake, but I mean to find out," said Nick. "If you'll hold the boat here, I'll climb up the bank and have a look round."

Jake took the boathook and Nick got out and set to climbing the bank. It was almost sheer, but the black volcanic rock was rough and broken, and he found good hand and foot hold, so he reached the top without much trouble. Very quietly and cautiously he rose to his feet and found himself on a rocky ledge some thirty feet above the water. So far as he could tell, there was nothing moving anywhere near, and once reassured on that point he began to take in his surroundings.

This was not too easy, for the light, which was bluish in colour, flickered abominably. Its source, Nick saw at once, was a great jet of blue flame which rose far away to the right of the river. At one minute this jet rose to a great height with a strong blue glare, then it died away to less than half its former altitude, jumping and flickering like a candle in a draught of air. When it rose it made a shrill piping sound, then, as it fell again, the sound died to a sort of thin whistle. Echoes from the vast vaulted roof overhead caught the sounds and sent them whispering all around in the most creepy and uncanny fashion.

"A gas geyser," said Nick to himself. "Well, the whole place is volcanic." Then gradually he noticed that the great jet was not the only source of light, for here and there he could see a dull red glow like that which might show from the mouth of an open furnace. These must be fire-holes, Nick thought, and what made him the more certain of this was the fact that the air, though breathable, was hot and close and left a nasty, sulphurous taste in his mouth.

As in the upper cave, there was vegetation in this place, but of a much lower order. There were moss bushes and a sort of lichenous growth, grey and scabby, which covered the rocks in many places. When the great gas geyser flared up he could see the livid hues lying in patches on the rocky floor of the cavern.

The more he looked at it, the less Nick liked it. His blood boiled to think that the dainty little Princess should have been dragged down into this horrible place, and he vowed that somehow or other he would rescue her. Yet the vast size of the cavern, the lack of light, and the poisonous atmosphere discouraged him terribly, and his spirits were very low as he turned and climbed carefully down to where Jake awaited him in the launch.

"What did yo' see, Marse Nick?" asked the black boy eagerly, and Nick explained as best he could. Jake shook his head solemnly. "I done told you dis was de bad place," he said. Then he brisked up. "Which way do yo' reckon we better go now?" he asked.

"Down the river, to begin with," said Nick. "There must be some place where Bastin landed, and we haven't seen one yet. Then I think we had better leave the launch and see if we can track him."

"Dat's de only way," agreed Jake, and once more Nick felt grateful for the pluck of this little coloured lad. He started up the engine and they went slowly and silently on down the river.

While Nick handled the launch, Jake kept a keen look-out upon the banks. He, as well as Nick, quite realised that their best—indeed, their only—chance of success was surprise. Bastin could not know or even suspect that they had managed to get the launch over the dam, and it would be disaster if any of the Owl Folk spotted them and carried the news to Bastin. But if the Owl Folk lived in this gruesome place, there was certainly no sign of them along the river, and the launch passed on over deep, black water between high, dark banks for more than a mile without her occupants seeing a sign of life.

"Marse Nick," said Jake at last. "I don't reckon nobody could live in a place like dis. I spect dat Bastin hab got through into some ober cave."

Jake's suggestion gave Nick a nasty jolt, for on the face of it, it sounded only too probable. If there were two of these gigantic caverns, why not a third or a fourth, or even more? The hopeless nature of their search came home to him with greater force than ever. Then, before he could answer, the launch rounded a curve and there on their right hand was a shelf of rock alongside which lay several of the metal canoes used by the Owl Folk, tied to ring bolts fastened in the rock.

Nick heaved a sigh of relief. "That's where Bastin landed, depend on it, Jake," he said, as he steered the launch in towards the rude wharf. "Do you see anyone about?" he added quickly.

"I don't see nobody," Jake answered, "but dat don't say dey ain't right near. Dere's a heap o' places all around whar folk could hide demselves."

It was true. The rocks behind the landing-place were broken and jagged, and in between grew thickets of stunted moss bushes. "You wait in the boat, Jake," said Nick, "While I have a squint over the top of the bank."

This time Nick took the precaution of carrying his crossbow with him, besides his sword, and crawled up the rock face as quietly as a cat. There was a sort of path sloping upwards, and Nick noticed that it had been worn smooth by the passage of many feet. Arriving at the top he crouched down and peered cautiously over the edge of the bank. The first thing he noticed was that he was now much nearer to the gas fountain than before, yet even so, that this was still two or three miles away; and the next that the path by which he had climbed from the river level ran straight away almost at right-angles to the river, towards something which, in the flickering blue light, looked like a small hill.

The light flared up more strongly, and Nick bit off a cry of astonishment, for now he saw that what he had first taken for a hill was, in fact a pyramid, of similar shape to that of Koom, but built of the same dark rock which composed the floor of the cavern. It was, of course, very much smaller than Koom, yet even so, it rose to a hundred feet or more above the floor of the cave. Nick took a pair of field-glasses from their case and proceeded to examine the building carefully. The glasses showed deep embrasures cut in the sloping walls and something in the nature of a gallery running round the summit.

He whistled softly. "Imitation is the sincerest flattery," he murmured, "but this is the limit. Who would have dreamed that those savages were up to a stunt like this?"

For a moment or two he lay quite quiet gazing at the Pyramid and wondering whether this was the prison in which Bastin was keeping his captives. Then, as there came one of the great spurts of blue flame from the geyser, he suddenly caught a movement among the rocks away to the left. Before the light died down he had seen a man bent double running rapidly away among the low brush. So Bastin, after all, had left a spy behind.

In a flash Nick was on his feet and in full chase. He was too wise to spring out into the open, but kept behind the ledge until he reached the screen of brush, then darted in among this and followed as hard as he could go.

The ground was shocking, all broken rock and brush. Since down here there was never any rain or frost, the rock was still much as it had been left ages ago by the terrific volcanic forces which had first formed these tremendous caverns. It was seamed with deep cracks and crevasses and littered with lumps of loose stone which were half-hidden by the low, wiry brush growing between them. The vast, flickering shadows formed by the alternate rise and fall of the gas fountain made matters even worse for Nick, and more than once he stumbled and almost fell. It was only the knowledge that it would be fatal to all his plans if the fellow got away that kept him on the track.

He had fully expected that the spy would make for the open path, but the man did nothing of the sort. Instead, he kept dodging in and out among the bushes and rocks. He went fast, but he was much smaller than Nick and his legs so much shorter, that soon Nick found himself gaining. As he got nearer, Nick was surprised to see that this was not one of the Owl Folk. At any rate, he had not the broad shoulders and bat-like ears of these uncanny people, and seemed altogether smaller and slighter.

Just then the little man turned his head and looked back, and Nick got a fresh shock of surprise. For the queer, mask-like face was like that of the Robots of Koom. Then Nick remembered how he had been told that some of the Robots had been stolen away by the Owl Folk. Undoubtedly this was one of their descendants, though he could certainly run faster than any of the puny little creatures who still remained in the Pyramid City.

Seeing that Nick was gaining, the little fellow gave a squeak of terror and turned sharply to the left into the thickest of the bushes.

Nick swung after him. He was getting nearer every moment and was confident of catching his quarry, whose head he could see bobbing above the bushes against the red glare of a fire-hole somewhere beyond. For a moment he lost sight of the chase among the jumble of spiky rocks. Next moment there came to his ears a sharp, shrill scream, horribly like that of a hare when badly wounded.

"What the mischief—?" Nick panted as he spurted forward, then he pulled up with a jerk just in time to save himself from plunging over the edge of a great pit. "Holy smoke!" he gasped as he wiped away the drops of perspiration which almost blinded him, and looked down into the dreadful depths below. Far beneath in the bottom of the pit crawled red veins of fire from which waves of heat beat upwards against his face, while the sulphurous fumes caught his throat chokingly.

In spite of the fierce heat he shivered, for the thought that he had driven a living creature into this fiery trap sent cold chills crawling down his spine. Just then there rose from somewhere beneath the same pitiful cry which he had heard before, and Nick, hardly daring to believe his senses, saw something moving on a ledge some ten or twelve feet below. A puff of stinging smoke hid it for a moment, then, as the mist cleared, Nick plainly saw the wretched little Robot lying on the ledge and struggling feebly. And—this was the ghastly part of it—if he went over the ledge he would drop straight into the red-hot depths and be simply roasted to a cinder.

Nick, as you may have gathered, was not a sentimental person, but the sight was too much for him. "I can't stick this," he muttered. "I've got to get him out." Then in a moment he was his hard, practical self again and searching calmly for a way down.

It took Nick only a few seconds to see that it was easy enough to get down to the ledge, but that the job would be to climb back, especially carrying the Robot. For a moment he thought of running back to fetch Jake and a rope, but the unfortunate Robot was still moving feebly, and every moment in danger of going over into the burning depths. If anything was to be done, it had to be done quickly, and Nick decided to take his chances. He slipped off his coat of mail and flung it aside, then went over the edge and started to climb down.

Waves of heat blasted and seared his flesh, while the sulphurous reek stung his eyes so that he could hardly keep them open. But he found good hold for hands and feet, and in less than a minute was safe on the ledge where the Robot lay. "Keep still, you fool," snapped Nick, grasping him.

The poor little creature at first tried to shrink away from him, but Nick swung him up on to his shoulder. "Hang on round my neck," he ordered; and though the dwarf could not, of course, understand Nick's words, yet somehow he caught their meaning and obeyed. A fresh cloud of smoke rose from the depths of the fire- hole, and Nick was forced to cover his face with his handkerchief until it passed. Then he set to the climbing. Luckily, the Robot weighed no more than a ten-year-old boy, yet even so the strain was frightful as foot by foot Nick clawed his way back up the almost perpendicular wall of rock.

Once a projection on which he had set his foot broke away and a great mass of rock went crashing into the depths with an ominous roar. For a moment Nick was left dangling by his hands against the face of the cliff, clawing desperately for foothold. Somehow he found it, but was forced to rest for a full minute before he could continue upwards. Quite how he managed the last few feet he never knew, and when at last he struggled over the edge and reached the level he collapsed and lay struggling for breath with his heart pounding like a hammer against his ribs.

"Marse Nick—Marse Nick, what's de matter? Am yo' hurt?" came a voice in his ear, and Nick rolled over to see Jake's frightened eyes looking down into his.

"What the mischief do you mean by leaving the boat?" Nick demanded angrily.

"What's de good ob de boat if yo' is dead?" retorted Jake.

"I'm not dead," growled Nick. "But since you are here, give me a hand with this beggar."

"Why, he's one ob dem Robots!" exclaimed Jake. "Whar yo' get him, Marse Nick?"

"I chased him, and the silly ass fell into the pit. I've had the dickens of a time getting him out."

Jake peered into the red depths of the fire-hole. "Jiminy Christmas!" he exclaimed. "Yo' tell me yo' went down into dat place? Yo' is crazy, Marse Nick."

"Stop jabbering, and help me carry him to the launch," said Nick irritably. "I only hope to goodness someone hasn't sneaked the boat while you've been away."

But when they had carried the Robot down to the river the launch was still there, and presently they got their prisoner aboard and Nick set to overhauling him. "Bit bruised, but nothing broken so far as I can see," was his verdict. "Give him a drop of that Kal stuff, Jake. If we can pull him round perhaps we can find out something useful from him."

Jake got out the flask and poured a few drops between the little man's lips. The result was astonishing, for at once the Robot's eyes opened and he gazed up at his captors with the expression of a beaten dog.

"Don't be scared," Nick told him. "We won't hurt you. Here—have a drop more." But the Robot shrank away.

"It's no use," said Nick despairingly. "We shall never make him understand." He dropped back into the stern of the launch and sat there looking so haggard and worn that Jake was scared.

"Marse Nick," he said, "yo' take some ob dat Kal. Yo' needs it worse dan dat Robot." He made Nick swallow a little, and, as before, it pulled him round.

"Thanks, Jake," said Nick. "I'm all right now. Sorry I made an ass of myself. I was getting a bit discouraged at not finding any traces of the others."

"But I done found some," was Jake's reply, and to Nick's intense amazement he suddenly drew from his pocket a tiny crumpled handkerchief.

"Chalma's!" exclaimed Nick. "Where did you get that, Jake?"

"It were stuck in a crack in de rock, boss, jest whar I climbed up arter yo'," Jake told him.

"Then she put it there on purpose," said Nick.

"Dat's what I tink, Marse Nick, cos she was de only one dat had her hands free."

"Then we are on the right track," declared Nick. "We'll go after them."

"Don't yo' reckon we better hab something to eat first?" suggested Jake. "It's a mighty long time since we all had any grub."

"Yes," said Nick. "Come to think of it, so it is. And we must hide the launch."

"Dat's gwine to be some job, Marse Nick. Dere ain't no place hyah whar we kin put her."

"We'll go down-stream a bit. There are lots of little creeks in the banks. I'm sure we can find a place. We'll do that first, Jake; then we'll have some grub and pack off."

Nick's energy was tremendous, and he did not lose a minute in casting off and starting down-stream. It was true, as he had said, that there were many little creeks and niches in the river bank, but it was not so easy to find one where they could hide so big a thing as the launch from prying eyes. "We're going too far down," snapped Nick at last. "We shall never get back to our starting-place."

Just then they ran into a sort of fog, and Nick, looking round, saw that it was vapour pouring from a rift at one side of the river, and promptly steered the launch towards it. "Watch out!" said Jake sharply. "Watch out or we'll get burnt up. Dat's one ob dem fire-holes."

"I believe it's only a steam jet," Nick answered as he came close in. "Yes, that's it, Jake. And just room to shove her under it." Now that they were close they both saw steam oozing from a vent in the bank about a man's height above water-level, and sure enough there was room to get the launch in right under it.

"That'll hide her," said Nick with a sigh of satisfaction.

"Ef it don't blow up and bust her all to bits," replied Jake uncomfortably.

"Don't worry about that," returned Nick. "It's been smoking like that for a few thousand years and I'll bet on its lasting our time. Tie her up tight, Jake, then help me get the grub and stuff up the bank."

The bank was steep and high, but Nick climbed it. Jake flung him a rope and they got up the loads, including a fair supply of food, the flask of Kal, their crossbows, and a few of the bombs. "Dat's de lot, boss," said Jake. "Now what yo' gwine to do about Flibberty hyah?"

"Bring him along. We can't leave him in the launch. He might scuttle her or set her adrift."

"I don't reckon he's got sense enough for dat," replied Jake with a touch of scorn. "But I guess we kin make him carry some ob our truck. Get right along up, Flibberty."

But Flibberty, as Jake called him, was no good at climbing, and Jake had to put the rope round him and Nick to heave him up. The poor little creature said nothing, and there was so little expression on his mask-like face that the others could not get the least idea of what he was thinking about. However, he no longer seemed so scared as he had been.

"And now, I guess, we'll hab supper," said Jake, as he joined Nick at the top of the bank.

"Supper!" repeated Nick. "More like breakfast. We've been hours down in this place already."

"I did reckon I was mighty sleepy," allowed Jake, as he poured some hot soup from one of the flasks they had brought with them.

"Are you getting fagged out, Jake?" asked Nick seriously.

"Ef I am, I ain't thinkin' of it," replied Jake. "I sure ain't gwine to sleep till we get de little lady safe."

"Nor I," said Nick grimly. "Give Flibberty the rest of the hot stuff and then let's be shifting."

"I knowed dem Owl Folk was monkeys first time ebber I seed dem," said Jake as he stood among the boulders near the fire-hole and gazed at the stone Pyramid in the distance.

"Monkeys—what do you mean?" demanded Nick.

"Becos dey jest imitates oder folk," explained Jake. "Dat Pyramid ain't nothin' but a sham, Marse Nick."

"A sham?" repeated Nick.

"Yes, sah, dat's what I tink. I can't see no door nor any ways in, and dere ain't no one movin' anywheres about."

Nick unslung his glasses, and for a second carefully surveyed the Pyramid. "Blessed if I don't believe you're right," he said at last. "Your eyes are pretty sharp, Jake."

"Dey ain't no better dan yours, Marse Nick, 'cept in dis funny light," replied Jake modestly.

"At any rate, they've spotted something that I never suspected," said Nick. "And something that I'm precious glad to know, Jake, for I was wondering how on earth we could get past that Pyramid place without being attacked."

"I tink we can walk right past widout no trouble," replied Jake. "But how yo' know we're on de right track, Marse Nick?"

"I don't," groaned Nick. "All I am going by is that there's a sort of path past the Pyramid and I suppose it leads somewhere."

Jake nodded. "I guess you're right, Marse Nick. Anyways, we knows dey started dis way, and it's a sure ting dey couldn't hab gone no oder way."

Nick felt that this was true, for if the going in the Upper Cave had been bad it was nothing to the state of the ground in these Outlands. Sharp-edged rocks were piled everywhere in the maddest confusion, and the floor of the cave itself was rent by great cracks and chasms, many of appalling depth. The whole place was one succession of death-traps, and Nick secretly wondered that even Bastin had had the courage to face the perils of this nightmare land. He snapped his glasses back into their case. "Come on!" he said curtly, and went forward.

The track wound in and out among huge boulders, which in places overhung it so as to cut off the blue glare of the gas flame, and leave them in deep gloom. They were getting nearer to the source of the light, and its whistling and piping came louder to their ears. Nick kept his eyes on the Pyramid, but with every minute that passed he became more convinced that Jake was right, and that the great, ugly mass of stone was merely a monument, for there was no sign of life about it.

When within about half a mile of the Pyramid the track turned away to the left, and ran through a sort of gorge where the air was thick with sulphur, and it was almost dark. "This is the place to trap us if Bastin knows we're here," thought Nick, but nothing happened, and presently they came out on to the edge of a large saucer-shaped hollow rimmed with black rock.

"Rum-looking place," said Nick, pulling up. "Which way does the path go, Jake?"

Jake did not answer, and Nick saw that he was gazing intently down into the hollow. "What are you looking at?" he demanded.

Instead of answering Jake darted forward, down into the bowl. Nick saw him stoop and pick up something. He held it up and Nick saw that it was a fragment of golden-hued cloth. "From de little lady's dress," cried Jake triumphantly; then all of a sudden he staggered and fell flat on his face, with arms outstretched.

For an instant Nick was paralysed with astonishment, but only for an instant. Then, as he darted forward, suddenly a hand clutched his arm and tried to drag him back. It was the Robot who was making strange clucking sounds, while for once there was an almost human expression on his mask-like face. Nick realised that the little creature was trying to persuade him not to go down into the hollow, and to tell him that some danger threatened, but there was no time to explain, even if he had been able to make the Robot understand. He shook him off and dashed to Jake's help.

He realised, of course, that Jake had been overcome by gas of some sort, and as he neared the spot where Jake lay he resolutely held his breath. Stooping, he swung Jake up on to his back and set to getting him up the slope. For a few steps Nick managed to carry on without breathing, but there are limits to that sort of thing. His lungs began to feel as if they would burst while his head spun horribly. His lips were forced apart, and the tainted air whistled into his lungs. Instantly he knew that he, too, was gassed, and a dreadful dizziness seized him. Yet he set his teeth and forced himself onwards.

A dozen steps and he would have been safe, but it was no use. Everything went black and down he crashed in a heap on the smooth, black rock.

That a band of iron was clamped round his head was Nick's first idea as he struggled back to the knowledge that he was still alive. He tried to raise his hands to his head, only to find that they were tied fast. Then with a great effort he opened his eyes to find himself looking straight up into Bastin's coldly evil face.

"So you still live, Mr. Prest," remarked Bastin with a faint touch of surprise in his chill voice. "You have more vitality than I imagined."

Nick made no answer. There did not seem anything to say, and in any case he was almost beyond the power of thought. Bastin stood looking down at him thoughtfully. "So you followed me. I fancied you might try it, and made my preparations accordingly." A mirthless smile curled his thin lips. "At any rate, they worked admirably, for you walked straight into my trap."

Bastin's eyes had in them something of the hideous fascination of a poisonous snake, but Nick's strength was coming back and he faced his enemy boldly. "Where is Jake Rodman?" he demanded.

"The black boy? He also is alive," Bastin answered. "I shall not kill him for the present, or you either." He spoke as calmly as if he were talking of the death of a rat or a rabbit, and Nick shivered inwardly. Yet he managed to keep a brave face.

"Thank you," he answered dryly. "Then may I ask what you propose to do with us?"

"I shall place you with the other prisoners while I make my arrangements with Phra. My good friend Kasim will care for you during my absence. Now we had better be moving. If you are unable to walk some of the dwarfs will carry you."

Nick shivered again at the thought of being handled by the hideous Owl Folk. "I can walk," he said briefly, trying to struggle up, but his bound hands made this impossible, and he fell back. Bastin stooped, and without the slightest effort, lifted him to his feet. The man's muscles were like chilled steel. "That way," he said, pointing to the left. "Walk in front of me, please."

Nick saw that Jake, in charge of a couple of Owl Men, was already on his way along the edge of the basin, but he could see nothing of the Robot. Flibberty had vanished completely. Nick, however, was too sore and miserable to give the little man a second thought. The knowledge that he had walked straight into Bastin's trap was almost too bitter to be borne.

It was, of course, Bastin, not Chalma, who had planted the clues for him and Jake to follow, and so he had saved himself the trouble of going to look for them. And now he and Jake were prisoners like the others, and all five at Bastin's mercy. So, too, was Phra and the whole of Koom, for Nick was definitely certain that Phra would think no sacrifice too great to get his daughter safely back from the Outlands.

It was all over. Bastin had won, and the treasures of Koom were his. The more Nick thought, the more terrible did the outlook seem to him. Nick Prest, being himself an engineer, was far better able than Jeremy or Mort to appreciate the terrible power which a man like Bastin could wield, once he was in possession of the secrets of Koom.

Armed with this knowledge, the man could, and would, make himself master of the world, and Nick was only too well aware of the use he would make of his power. With his immense intellect, his inhuman lack of conscience or pity, he might entirely destroy modern civilisation, and fling mankind back into the black horrors of the Middle Ages.

The prospect was so appalling that, for the time, Nick hardly gave a thought to himself or to his surroundings, but walked mechanically onwards. What roused him was a roar and a great glow of light, and suddenly he realised that they had come out of a narrow defile, and were on a wide and level plateau in the centre of which rose the great gas geyser.

"An amazing waste of energy, Mr. Prest," remarked Bastin quietly. "Our friends in the Upper Cave would make better use of it. Even if the flame were capped with a suitable mantle it would light this place like a sun."

Nick did not answer. He felt once more the thrill of repulsion with which Bastin always inspired him. He would have preferred the roughest, most brutal treatment to the smooth voice and polished phrases of this passionless scoundrel.

Out on the far side of this level space stood a curious island-like mass of rock. The leaping glare of the gas fountain was reflected from the shining surface of this rock, which had the appearance of being made of black glass. Bastin raised his arm, and pointed to the island.

"That is where you will find your friends," he stated. "And, as you will presently discover, it is a prison somewhat safer than one built of bricks and mortar."

Nick gazed at the glassy island, but could make nothing of it, and he was certainly not going to ask questions of his gaoler. He saw that Jake was being led round to the right of the flat plain and Bastin followed in the same direction. As they came nearer to the edge of the plain a new odour came to Nick's nostrils, an odour which, in some odd way, brought back to his memory the streets of London on a hot summer's day. Next minute he recognised it for that of asphalt pavement, and in an instant he knew all about it.

The plain was no plain, but a lake of pitch like that of the island of Trinidad.

Bastin seemed to read his thoughts, and once again the cold smile crossed his face. "I see that you understand, Mr. Prest, and I feel sure that a phenomenon like this, found so far underground, will prove of interest to a man of your scientific mind. There would, of course, be a fortune in it, were it on the surface instead of in these infernal depths. It is, however, of direct value to me, as you will presently understand."

He led Nick along the edge of the lake until they reached the far side, and here on a point of rock, running out into the lake, Jake and his escort were waiting.

"What dey gwine to do wid us, Marse Nick?" asked Jake in a low voice. "Do yo' reckon dey'll drown us in dis hyah great black pond?"

"No, they're going to take us to that island," Nick whispered back, but before he could tell Jake anything more Bastin was beside him.

"You will now be taken to the island," he said, "but since it is essential to my plans that you do not find your way back, I must first blindfold you."

As he spoke he slipped a sort of bag over Nick's head and tied it around his neck. Nick's flesh crawled at the mere touch of Bastin's hands, and at the moment he would cheerfully have given his life for a moment's freedom and the possession of a pistol. But with his wrists tied behind him he was helpless and forced to submit.

"No harm will come to you so long as you remain quietly upon the island," continued Bastin in his quiet level tones. "But let me warn you against any effort to escape. The path is known only to the dwarfs and myself, and any attempt to reach the shore can only end in a slow, sticky and unpleasant death."

There was a short pause, then Nick heard Bastin speaking to the Owl Men in their strange clucking tongue. At once one of the horrible creatures took him by the arm, and he was led out across the level surface of the lake.

Nick set himself carefully to count the steps, but soon realised that this was entirely useless, for his guide led him in such curves and twists that within a very short time he no longer had the faintest idea of his direction. It seemed to him that he must have walked a mile before at last his guide stopped.

"Nick, old man!" came a deep voice, and the bag was whipped off his head by Jeremy himself. "You poor old chap!" said Jeremy. "So they got you, too."

"As you see," replied Nick bitterly. "Jake and I simply ran our heads into it. Loose my hands, Jeremy, then I'll tell you."

The Owl guards made no objection to Jeremy untying the cords around Nick's wrists and then doing the same office for Jake. "Where are Chalma and Mort?" was Nick's first question.

"Asleep in their sheds," replied Jeremy pointing to some stone pens standing on the higher part of the island. "We built that ourselves to give us some sort of privacy, but it was pretty hard work, and they are both played out. I was just going to sleep myself when I spotted you with Jake and Bastin on the edge of the lake."

"And realised that I'd chucked away your last chance," said Nick miserably.

Jeremy laid his big hand on the other's shoulder. "Not a bit of it," he said cheerfully. "I was only too glad to think that we should have your quick brains to help us. But come and sit down, for you look as if you have had a pretty rough passage, and I want to hear all about it. We can talk quietly so as not to rouse the others."

The island was very small, not more than half an acre, and it was only a few steps round to the back of the stone pen where Chalma and Mort were sound asleep. The two Owl Men had squatted down near the landing-place and were paying no attention to the prisoners. It was quite plain that they knew them to be safe. But Nick glanced round suspiciously.

"Where's Kasim?" he demanded.

Jeremy pointed to a tent-like erection at the far end of the island. "In there," he whispered. "Thanks be, he does not interfere with us. He only keeps an eye on us and brings us grub."

"They do feed you then? That beast, Bastin, told me that he meant to starve you until Phra gave in."

Jeremy shrugged his great shoulders. "He was not far wrong. We get some soup-like stuff about once in ten hours. I don't know what it's made of, and I don't think I want to, for it's pretty beastly. But sit down and tell me all about your own doings."

He stretched himself with his back against the wall and his long legs extended on the smooth, black rock; Nick and Jake sat down beside him, and while the gas flame sent weird shadows leaping across the wide lake of pitch Nick told Jeremy all that had happened since Bastin had sent him back to Koom with his terms. "And now Bastin is going back to see Phra himself," he said. "And I needn't tell you what that means, Jeremy."

Jeremy nodded. "No, I can't see Phra holding out for long when he knows that Chalma is down here."

"He won't hold out for five minutes," returned Nick forcibly. "And it's the finish, not only for us, but for civilisation, if that fiend gets loose on the world with all the stored-up knowledge of Koom."

Jeremy looked thoughtful. "You think Bastin will finish us before he clears out?"

"Of course he will. He is not going to risk our getting loose to put a spoke in his wheel."

"No, I suppose not. Then, Nick, we've got to get out of this on our own. And the sooner the better, for the air is bad, and Chalma can't stand it for long."

"What's the use of talking like that?" snapped Nick. "Flies might as well talk of getting off sticky fly-papers."

"It's not so bad as that, Nick," replied Jeremy calmly. "We know there is a way across the pitch lake, and you seem to have hidden your launch so well that I doubt if even Bastin will find it. We must put our heads together and knock out a plan. After all, there are four of us men, and we ought to be a match for Kasim and his dwarfs. There are only three of them on this island."

"You forget that Kasim is armed and that nothing would give him more pleasure than to shoot us down."

"I don't forget that for a moment, Nick," Jeremy answered gently. "If Kasim hadn't had a gun I should have tackled him some hours ago."

For a moment Jeremy's jaw tightened, and the idea flashed through Nick's brain that he would not care to be in Kasim's shoes if Jeremy ever got his chance at him. Then he went straight back to the question in point. "Of course Bastin didn't leave you any weapons?"

"Not even a pocket-knife," Jeremy answered. "He stripped you, too, I suppose?"

"Yes," said Nick. "At least I suppose so. He had a good chance while I lay gassed. Still I may as well go through my pockets."

He began to do so. He pulled out a handkerchief, a watch, a little silver lighter, and a pocket-book. "That seems to be about all," he said, then suddenly he thrust his hand down into the left hand inner flap of his thin tweed jacket, and Jeremy heard him give a queer little gasp.

"Found something?" he asked.

Nick drew out a small, oval-shaped case of grey metal. His fingers shook a little as he held it up. "By gum, Jeremy, but I should think I have," he answered.

"What is it?" questioned Jeremy.

"A smoke bomb. Bastin must have missed that pocket altogether."

Jeremy looked rather disappointed. "A smoke bomb," he repeated. "What's the use of that?"

Nick fingered the little case lovingly. "Properly used, it may save the lot of us," he said quietly. And even as he spoke a slight sound made them both look up, and there was Kasim standing over them, gazing down upon them with all the evil in the world in his narrow, greenish eyes. In his right hand he held a pistol, his left he stretched out to take the metal case from Nick's hand.

Nick seemed to shrink and cower under the deadly threat of the automatic. His hand shook as he extended the metal object towards Kasim—shook so that the case dropped from his nerveless fingers and fell upon the glass-hard rock between them. There came a pop no louder than the bursting of a toy balloon, then in an instant everything was black as night, and in the same fraction of a second Nick flung himself sideways.

Through the ink-like gloom Kasim's pistol spat red flashes, and two reports in rapid succession crashed across the lake, rousing thundering echoes. Followed a scream as Kasim's neck was gripped from behind by Nick's fingers, then with all Nick's weight upon his back the man crashed forward to the ground with stunning force.

"The gun—get the gun, Jeremy!" cried Nick as, kneeling astride his enemy's body, he banged the man's head against the rock.

"I've got it," came Jeremy's voice out of the gloom.

"Then get those dwarfs," ordered Nick as he ripped out his handkerchief, and, wrenching Kasim's hands round behind his back, tied his wrists tightly together.

The reek was rising and thinning, but Nick was half-choked as he struggled out of it and bumped blindly into someone who came running up. "Say, what's up?" came Mort's high-pitched voice. "Gee, but if it ain't Nick!" he gasped.

"We've got Kasim," snapped Nick. "But look out! Here come the dwarfs!" Even as he spoke a slingstone whizzed viciously past his head. Then the pistol cracked again, and a hoarse cry told Nick that Jeremy had shot straight. Another shot, and another, then Jeremy's great voice. "All right, Nick, bagged the lot. The island is ours. Where's Kasim?"

"He won't trouble us again in a hurry," said Nick grimly. "Get along to his tent, Jeremy, and see if there are any cartridges. We've got to be ready against reinforcements."

As Jeremy went with long strides to the farther end of the island, suddenly Nick found a pair of soft arms round his neck. "Nick! Nick! Oh, brave Nick!" cried Chalma, and kissed him on both cheeks.

Nick, rather red in the face, kissed her back. "Princess, we have knocked out Kasim," he told her. "Now, if we can only cross the lake we have a chance of getting back to Koom."

Jeremy came hurrying back. "I've found a second automatic and a big bunch of cartridges," he said. "What's almost better, I have a couple of big cakes of chocolate and some sticks of dynamite."

"Good business!" exclaimed Nick. "I told you that smoke bomb might turn the trick. Now we've got to find our way back to the shore."

"That's the rub," replied Jeremy. "In any case, it will be a long job, and if the Owl Men turn up in force we can't hope to do it."

"Where are they?" demanded Nick. "Except these few, I haven't seen horn or hoof of them since I got down into this black hole of sin."

"They live in burrows high up in the wall of the cavern," explained Jeremy. "The air is better up there, I expect. But they must have heard the shooting, and the odds are that they won't waste much time in getting after us."

"All the more reason why we should clear out quickly," said Nick. "See, here, we'll take the spears from these dead Owl Men, and use them to probe our way back. Come on!"

It was a matter of only a few moments to collect the spears, then they went down to the spot where the trail ended; and, with Jeremy in the lead, started out.

Nick had hoped that the tracks made by those coming to and going from the island would be visible, but he soon found that this was not the case. The surface of the pitch was so soft that any marks made filled in a few minutes. Every step had to be tested before it was taken, and at almost every other trial the spear sank deep into a substance almost as soft as treacle. It made Nick shiver to think of what would happen if one of them make a mistake.

The trail, such as it was, wound in and out in every imaginable twist and turn, and it was maddening to be forced to go so slowly when there was such bitter need for haste, yet by degrees they gained distance and left the glass island farther and farther behind.

Nick and Jeremy took turns to probe the way, while Mort and Jake kept a keen watch on the shores, and between them helped Chalma along. Half an hour had passed, but they were still a couple of hundred yards from the edge of the lake when Jake raised the alarm. "Dey is coming, Marse Jeremy," he said. "I done seed the blue light shine on spears away on de hill ober dere."

Jeremy glanced in the indicated direction. "Yes, I see, about a mile away, I should think, Nick. That gives us—say—ten minutes."

"That's about all," replied Nick curtly. "Get on, Jeremy."

But Jeremy had come to a dead stop, for wherever he tried the pitch in front the spear sank deep into soft stuff. "It's no use, Nick," he said at last. "We're on the wrong trail altogether. There's nothing for it but to make back."

"Then that sees our finish," were the words that flashed through Nick's mind. But aloud he said quite calmly. "All right, Mort, let me pass you so as to try back."

Back they went as far as the footmarks still showed, then began again with desperate haste to hunt for a surface that would bear their weight. It was no use, for they could find none. Between them and the shore there appeared to be a belt of soft stuff—so soft that it would not bear the weight of a cat, let alone of a man, and there did not appear to be any way of crossing it.

"Dem Owl Folk is coming on right smart," said Jake in Jeremy's ear. "I guess we got to go back to de island, Marse Jeremy."

"It looks rather like it," replied Jeremy, and though his deep voice was steady as ever, Nick saw something like despair in their leader's steady grey eyes. As Nick turned he thought he saw a movement among the boulders by the edge of the lake. He paused an instant, and, as the great gas flame rose roaring towards the cavern roof, he distinctly saw a small figure come scuttling down towards the shore. Jeremy saw it, too, and raised his pistol, but Nick caught his arm. "Steady, Jeremy. That's no savage. It's my pal, the Robot."

"You's right!" exclaimed Jake. "It's Flibberty."

He beckoned violently to the little man, and next moment the latter had stepped boldly out on to the surface of the lake.

"He knows the way. He's coming to help us," gasped Mort, and next moment the others saw that Mort was right. How Flibberty found his way was beyond guessing, for there were no landmarks, yet the little fellow never hesitated for a moment, but came on at a sharp jog-trot. In a couple of minutes he was with them, and, making straight for Nick, began jabbering away in his extraordinary language.

Nick could make nothing of it, but Chalma understood. "He tells us to follow him," she explained. "He says that he can show us a way to escape the Owl Folk."

"Then tell him we'll follow him till this pitch freezes over," returned Nick, and, after a word from Chalma, the Robot turned and trotted briskly back. He was so quick about it that the whole party reached the bank well before the Owl Folk were in range. Then he turned sharp to the left and beckoned the others to follow.

"We're running right into the enemy," said Jeremy uncomfortably, but Nick watched the Robot. "The little beggar knows what he's about. Give Chalma a hand, Jeremy, and let's run for it."

Shrill cries came from the Owl Men as they saw their prey escaping and they broke into a run. As they came pouring down the slope Nick saw that there were at least forty of them. With their brutish faces and pointed ears they were a terrifying sight, and Nick's very soul shrank at the thought of what would happen if they were caught.

Flibberty ran harder than ever and Nick's heart pounded as he tried to keep up. He had not yet recovered from his gassing and felt he could not last much longer. Luckily for the fugitives, the shore of the lake was flat, while the ground beyond was fearfully rough, yet even so when the little party reached the left-hand corner of the lake the leading savages were within less than two hundred yards.

Flibberty pointed ahead and Nick saw a ridge of rock cut by a narrow defile. He realised that this was a refuge of some sort, and shouted to the rest to make a last spurt. The dwarfs saw it, too, and increased their speed. Jake began to fail. He stumbled badly, but Mort pluckily seized him and pulled him on. Nick saw Flibberty dive into the defile and Jeremy swing Chalma in. His own head was spinning and his legs felt like lead.

The savages were gaining, and slingstones began to whizz viciously around him. A stone had struck Jake between the shoulders and he flung up his arms and fell. As Mort tried bravely to lift him, he, too, was hit and went down.

"That's the finish," said Nick grimly, and whipping out his pistol turned at bay.


CHAPTER VI

Crack! Crack! Crack! In the heavy air Nick's pistol roared like a cannon. All five shots he fired, but panting with his long run his hand was so unsteady that only one of the Owl Men dropped. The rest, with high-pitched screams of rage, set fresh stones in their slings, and Nick saw that it could only be a matter of moments before he would be in the same case as Mort and Jake. Yet he stood and faced them, meantime thrusting a fresh clip of cartridges into his weapon.

"Lie down!" came a shout from behind him. "Lie down, Nick, and they won't hit you."

Then, before Nick could realise what was happening, Jeremy came charging past him, swinging something that looked like a club around his head.

Nick shrieked at him.

"Get back, Jeremy. Get back. You're crazy. You must not leave Chalma."

All Jeremy's answer was to charge onwards, and so startling was the effect of this single-handed attack that the Owl Men were plainly alarmed. They lowered their slings and gathered closer together.

Jeremy suddenly stopped, stood perfectly still, then, taking a matchbox out of his pocket, struck one, and deliberately touched it to the end of his weapon, which Nick now saw was a stick of dynamite ready primed.

The Owl Men recovering from their scare, shrieked again, and stones began to whizz viciously all round Jeremy.

By a miracle not one hit him, and raising the stick of dynamite with its sputtering fuse, he flung it with all his force straight at the mob of savages. High it flew in the air, and dropped plumb in the midst of them. A great flash, a blaze of light, an explosion that sent Nick staggering backwards and seemed as if it must crack the great dome of rock that arched overhead. The ground heaved, and the roaring echoes left Nick deaf and stunned.

As for the wretched Owl Men, not one remained upon his feet. They were flung right and left like ninepins, and Nick saw that many of them would never rise again.

Jeremy did not waste an instant, but came running back to Nick. Seizing Mort, he swung him up on his shoulder as easily as though he had been a child.

"Can you manage Jake?" he called to Nick, and Nick, catching up the little coloured boy, staggered away after Jeremy. Jeremy, running hard, reached the narrow pass between the rocks, dropped Mort and came racing back to help Nick. A moment later they were all safe in the narrow defile.

"Hold the entrance, Jeremy," gasped Nick, and done to the world, let Jake slide to the ground and dropped beside him.

"Nothing to hold it against, old chap," replied Jeremy. "The Night Folk who have any legs left are still running." He turned to Chalma. "Princess, give Nick another drop of that Kal stuff. I've got to see to these other lads."

One sip of the wonderful cordial put fresh life into Nick, his breathing became quieter, his heart stopped thumping, and he was able to sit up.

"What about Mort and Jake?" he questioned anxiously.

"Jake's all right," Jeremy answered. "The stone got him between the shoulders and knocked the wind out of him. But Mort had one on the head, and there's a lump like an egg."

"And it sure ain't going to hurt any less if you keep on fingering it," came Mort's voice.

Jeremy laughed outright. "Seems I needn't have been so scared," he remarked. "But honestly, how do you feel, Mort?"

"Like I had two heads instead of one," grumbled the American. "Say, who pulled me out of it, and who made that there earthquake?"

"That was Jeremy," said Nick. "He did it with a stick of dynamite. He also hauled you in."

Mort sat up and thrust out his hand. "Gee, Jeremy, seems to me you got a kind of monopoly on this here rescue stunt. I guess next time it's my turn."

"You'll get your turn all right, Mort," replied Jeremy. And now his tone was grave enough. "We're a long way still from being out of the wood. That explosion must have been heard by every pair of ears in the Outlands, and it's bound to bring Bastin back on our track. If the Night Folk rally, we shall be between two fires. What do you think, Nick?"

Nick did not answer at once. He was watching Flibberty. The little man was pointing back down the defile where a red glare shone out, then he pointed to his eyes, and last to the open ground outside the pass.

"What's he mean?" Nick demanded. It was Chalma who explained to Jeremy, and he translated. "He is telling us that we are safe from the Owl Folk so long as we keep by the fire-holes. They can't stand the glare."

Nick's anxious face cleared a little. "That gives us a breathing space," he said. "See here, Jeremy. Get Chalma to ask Flibberty how far the fire-holes reach, and if they'll take us back to the river."

Chalma talked to the little Robot for some moments. Then she translated to Jeremy. "They take us nearly all the way," said Jeremy to Nick.

Nick nodded. "Then, as soon as Jake and Mort are fit, we had best make tracks for the launch. Don't you think that's the best scheme, Jeremy?"

A serious expression crossed Jeremy's face. "It seems to me, Nick, that everything depends upon Bastin. He must have heard that explosion, and it's a sure thing he'll realise that we've got clear."

"I don't see that," interrupted Nick. "I agree that he will realise something is wrong, and that he will probably make back tracks. But, in my opinion, he'll go first to the pitch lake."

"And there he will find Kasim," said Jeremy, "and Kasim, of course, will put him wise to all that's happened."

"Yes," said Nick, "but then they'll both be behind us, and, if we make a dash up-stream, we ought to get clear away before they can catch us."

Jeremy shook his head. "You're a bit too hopeful, Nick. Bastin's no fool, and it's a thousand to one that if he does do as you suggest he will first put a pretty heavy guard on the tunnel."

Nick's face fell. "I suppose he will," he said reluctantly. "Still, they will only be Owl Folk, and with our pistols and dynamite we should surely have a chance of smashing and getting through them. Anyhow, it seems to be our only chance."

"I guess Nick's right, Jeremy," put in Mort in his quick, high-pitched voice.

Jeremy shrugged his great shoulders. "I've got to confess that I can't suggest anything better," he said, "so if you lads are up to tramping it, we'd better push along. Flibberty knows the way and he will guide us."

The way, as shown them by the little Robot, was a precious stiff one, and the distance was greater than any of them had thought. Every now and then Jeremy called a halt, and the party stopped while one of them climbed a rock and had a good look round. But the farther they got from the gas fountain, the worse the light became, and when at last they reached the river bank, they had not seen the slightest trace of any of their enemies.

The launch remained where they had left it. So well hidden was it by the steam jet, that they themselves were quite unable to see it until they were close upon it. Jeremy helped Chalma down the steep bank, and, in a few moments all six of them had safely embarked.

Nick at once started to untie the rope, holding the launch to the bank, but Jeremy checked him. "One minute, Nick," he said. "As I came down the bank I've a notion that I saw the gleam of grey metal a little way up on the far side just where the river is narrowest. If Bastin has had sense enough to plant a force of Owl Men just there it's going to be mighty awkward for us."

Nick glanced at the spot which Jeremy had pointed out. "You're right, Jeremy," he answered unhappily. "It will be very awkward, indeed. But what are you going to do about it?"

"Find out if they are there," replied Jeremy simply, and, without another word, went clambering back up the bank.

The mist from the hot spring was so thick that there was little risk of Jeremy being seen by the enemy. Yet, for all that, the other five were very anxious as they waited for their leader's return. Minutes dragged by, each seeming as long as an hour, and still there was no sign of Jeremy.

"Say, he's taking a mighty long time," said Mort at last. The words were hardly out of his mouth when Jake, who was watching the river, gave a queer gasp. "Watch out, Marse Nick," he hissed. "Dere's something a-coming down de river, and it looks to me like one ob dem submarines."

All eyes were turned on the stream. Round the bend above a wave rose into sight, and bore down upon them with great speed. There was no time to do anything. In a flash the wave and whatever had caused it had passed and went rushing away down- stream. The back wash flung the launch sideways, and a quantity of water splashed over the coaming, but, luckily, did no further damage.

"Say, whatever was it?" breathed Mort.

"I sure seed something big and black under de water," said Jake. "Looked to me like it was longer dan dis here launch."

Nick gave a sharp little exclamation. "I know. It was Krah—no, not Krah, but Krah's mate. She must have come down through the tunnel, and now she's scared stiff and running amok."

"I guess you're right, Nick," said Mort gravely; "but where d'you reckon she'll go now?"

"There's no saying," Nick answered, and even as he spoke Jeremy came sliding silently down the bank and into the launch. "It was Krah's mate," were his first words. "I saw her plainly. So did the Night Folk."

"So they're there," said Nick gravely.

"They're there, all right," Jeremy answered, "a score or more of them. They're lying along a ledge just above the river and a little beyond the bend, and they've got big rocks ready to drop on us."

Dead silence followed this unpleasant announcement. Mort was the first to speak. "Looks to me like we're properly up against it," he said slowly.

Nick was the first to make any useful suggestion. "What price that other stick of dynamite, Jeremy?" he questioned. "S'pose I take it and crawl up to the place you've just come from; I could chuck it across the river right on top of them."

"I've thought of that myself," Jeremy answered. "The objection is, that even if we do wipe them all out we advertise our presence to Bastin. Besides, we have only one stick left, and I'm not sure that we might not find a better use for that."

"Better use?" repeated Nick.

"Yes. What about bombing the big gas jet, and leaving the whole cave in darkness?"

The suggestion was so startling that, for a moment, no one found anything to say, and while they considered something else happened. Suddenly a canoe came shooting round the bend driven by four Owl Folk paddlers. And in the stern sat Kasim.

With one accord they all shrank down, but they need not have troubled, for even Kasim's keen little eyes could get no glimpse of the launch, hidden, as she was, under the bank in the thick fumes of the steam jet. The canoe passed within a dozen yards, so closely that they could plainly see Kasim's face with its long nose, lipless mouth, and expression of such evil as made them shiver.

Travelling at great speed, the canoe shot around the next bend and almost instantly vanished from sight. Mort spoke. "Say, he was hunting us."

"And we let him go," added Nick bitterly.

"He will come back," said Jeremy. "He's sure to come back when he doesn't find us. Then we'll be ready for him."

"Wait for him here, you mean?" said Nick.

"Yes, then collar him, stick him up in the bow of the launch, and mark him Exhibit A for his pals above."

Nick grinned. "Good egg, Jeremy. They'll think twice before pitching those rocks on to their beloved leader."

As they settled down to wait Mort made a suggestion. "Nick," he said plaintively, "I dunno how you feel about it, but I'm plumb starved. If there's any rations in that stern locker, I could do with a bite."

"Rations," repeated Nick, "of course there are. Lashings of them. Jake, rake out some of that grub, and pass it round."

In their excitement they had forgotten how hungry they were, but now they all did justice to the good things which had come from Koom.

"I'd almost forgotten what real food tasted like," said Mort, as he bit into a delicious sandwich.

The meal did them all good and put them in better spirits, but time passed, and there was still no sign of the return of Kasim.

Suddenly Chalma, who, like the rest, had been watching the river, gave a slight exclamation, and, turning to Jeremy, said something to him in a quick, low voice. Then Jeremy looked down at the water, and Nick saw a puzzled expression on the big man's face.

"What's up?" he asked.

"The water's rising," replied Jeremy.

"The water rising," repeated Nick, raising his eyebrows. "By gum, but you're right. Is this some new trick of that beast Kasim?"

Jeremy shook his head. "That's not likely," he said slowly. "If he or his men had blocked the lower outlet, it would be as bad for them as for us."

"It's sure rising," observed Mort. "Say, but this is a funny business."

Nick started up suddenly. "I've got it. I'll tell you what's done it." He paused a moment, while all the rest sat silent gazing at him. "That big beast," he continued. "Krah's mate, I mean. We saw her go downstream. It looks to me as if she had charged down the lower tunnel and got jammed there."

Jeremy pursed his lips in a silent whistle. "I never thought of that, but I haven't much doubt you're right, Nick." He paused and considered a moment. "But if you are right, this alters everything."

"How do you mean?" questioned Nick. Then, before Jeremy could answer: "I see," he added, "a bust-up."

"Yes," said Jeremy, "once the water reaches the fire-holes, there's bound to be an explosion."

Nick looked anxious. "Then the sooner we're out of this the better," he said quickly.

Jeremy remained calm. "What's the use of hurrying?" he asked. "It seems to me that, of the two evils, the stones up on that ledge there are by far the worst. They're sure to sink us, but I don't believe the explosion will—at any rate, not the first one."

"Then you advise waiting?" said Nick.

"Yes. My idea is that the first explosion will put the wind up those dwarfs, and then will be our chance."

"But we may have to wait hours."

"Not with the river rising as fast as it is. Look, you can see it crawling up. Remember, there's a big lot of water coming down from above. If you ask me, it's already over the bank down below."

Nick nodded. "Your advice is generally pretty sound, Jeremy. I'm game to wait. What do you other chaps say?"

"Me for Jeremy," said Mort promptly.

"Dat's my notion, too," agreed Jake. "What does de little lady tink?"

Jeremy spoke to Chalma, and the others saw that she, too, agreed to what he said. By this time they could all see that the water was banking up with a vengeance. There was no longer any current visible, and the rocks on either edge of the water were steadily vanishing. There was still no sign of Kasim.

"Say," remarked Mort presently, "I reckon Bastin must be getting anxious. He dunno where we are, and he's lost Kasim. What d'you reckon he's doing?"

Nick touched Mort's arm and pointed upstream. "Here's your answer, my lad," he whispered; and as he spoke they all saw another canoe swinging around the bend above, and in the stern sat Bastin himself.

Mort quivered with excitement. "Gee, but this is great!" he muttered, and grabbed for his crossbow.

Jeremy caught him by the arm. "No," he said curtly. "Let him pass. If we start a row now we have the dwarfs to reckon with."

Bastin's canoe was barely around the bend before there came, from the lower end of the cave, a loud boom followed by a fierce, hissing sound. The heavy air shook with great waves of sound, and the rocks around them quivered with vibration.

"The first fire-hole," said Jeremy under his breath, and, as he spoke, Bastin's paddlers paused, and all in the launch saw terror plainly expressed on their hideous faces. But Bastin shot out a savage order, the paddles dipped again and the canoe drove forward.

"Looks to me like Bastin's getting kind of worried," remarked the irrepressible Mort. He was right, for, as Bastin passed almost within arm's length, the boys could plainly see the look of anxiety in his bitter ice-cold eyes.

Chalma sighed with relief as she saw their cruel enemy vanish around the next bend.

"He's got pluck, anyhow," said Nick. "I wouldn't care to go any closer to the scene of that bust-up."

"Of course he's got pluck," agreed Jeremy. "That's what makes the chap so dangerous. All the same, I think that sounded worse than it really was. There are only a few small fire-holes at the lower end. The trouble will come when the water reaches the larger ones, which we passed on our way back here."

"And that won't be a thing to what'll happen when it gets to the big gas pipe," said Mort.

Jeremy looked grave. "You're right, Mort. Once the water reaches that geyser it will probably blow the stuffing out of the whole show."

"Will it wreck Koom?" asked Mort in sudden alarm.

"I don't think so," answered Jeremy. "I hope not, anyhow. There's a pretty good thickness of rock between the two caves, and nothing volcanic in the upper one. Koom, too, is pretty solid."

"But what about the water?" asked Mort. "Won't it pile up and fill both caves?"

"Why should it? The air here, if a bit thick, is breathable. That means there's ventilation, so there must be openings somewhere in the walls, and they will give the water a chance to escape. Even if the worst comes to the worst, it will take a long time to drown out Koom. The people will have plenty of chance to get away."

Nick spoke. "The light's getting very queer, Jeremy," he said quickly.

"That's what I expected," replied Jeremy. "It's fog from that explosion. I'll tell you what, Nick, I will climb up the bank again and spy out the land." As he spoke he was out of the launch, and, under cover of the mist, clambering rapidly up the rock wall of the river. For so big a man he moved with wonderful swiftness and silence, and in a moment or two had vanished among the loose boulders at the top of the bank.

The rest waited in silence until he reappeared.

"It's all right," said Jeremy, rather breathlessly, as he slid back into the launch.

"They've all gone. There's not a sign of them left."

"Then the sooner we follow them, the better for us," said Nick swiftly. "D'you agree, Jeremy?"

"Most certainly, I agree," Jeremy answered. "We've got the legs of Bastin and Kasim, and if we can fight our way through the Night Folk, I really believe we ought to get clear."

To all of them it was an intense relief to get once more under way. Nick handled the engine; Jeremy, with a pistol in one hand, steered with the other. Mort had the second pistol, and Jake, in the bow, kept a keen watch on either bank. As they passed beneath the ledge where Bastin had laid his ambush, a second explosion sent heavy echoes booming through the great rock vault, and they all saw a vast column of white mist rushing up towards the roof. The fog was thickening every moment, and although the great flame of the gas geyser still blazed up at regular intervals, the light was becoming extremely treacherous.

"That will bring Bastin back," remarked Nick.

"Yes, but we have the legs of him," replied Jeremy comfortingly. "Unless we're stopped, he won't catch us."

The pace of the launch slackened, for now they were above the flooded area and driving against the full force of the stream. Once or twice they saw small bodies of the Night Folk racing madly among the rocks, but the savages were evidently too frightened to make any attempt to attack.

They had covered about a mile when Jake pointed to an opening in the right-hand bank. "Dere's a creek, boss," he said to Jeremy.

"You're right, Jake," Jeremy answered. "We didn't spot that on the way down."

"A heap o' canoes in it, too," added Jake.

"I see them," said Jeremy. "It must be a sort of port for the Night Folk."

"A good place to get away from," said Nick curtly, and putting on all the power possible, he sent the launch rushing past the opening.

The gas fountain flared up in one of its great blazes of light, and through the wet, drifting mist they caught a glimpse of a great blackness, which was the upper wall of the cave. "Another half-mile," breathed Nick. "Another half-mile and we fetch the tunnel."

"And Bastin's a long way behind us," said Mort. "Say, boys, but it's almost too good to be true. What makes you look so grave, Jeremy?" he added.

"The fact that I know Bastin a little better than you, Mort," was Jeremy's answer. "I don't want to discourage you, but if you think that Bastin is going to let us go out without even saying good-bye, you've got another guess coming."

Mort's face fell so sadly that Jeremy hastened to comfort him. "I mean we'll have to do a bit of fighting, Mort. You see, Bastin is sure to have put a guard on the mouth of the tunnel."

Mort looked relieved. "That don't worry me none," he remarked. "I'll be only too pleased to get a bit of my own back on those Bat Folk. I'm real anxious to hand one or two of em' a crack like the one I got from that bit o' rock."

Nick kept the launch at top speed, and, with each moment that passed, the wall of the cave showed up more clearly through the whirling mist wreaths. "One more curve," said Nick, "then we'll see the mouth of the tunnel and know what's coming to us."

For the next few moments there was a breathless silence, while all six pairs of eyes gazed keenly up-stream. Even little Flibberty's mask-like face showed a certain anxiety. Then, as they drove silently round the last bend, Mort exploded into a sort of gasp of relief.

"There ain't no one there!" he exclaimed.

Apparently he was right. There were no canoes visible, and certainly no Bat Folk on the bank.

"Say, but this is great," remarked Mort, with much relief. "I don't reckon I was hankering after a lot of fighting."

Jeremy turned to him. "Sorry to disappoint you, Mort, but I'm afraid you're going to get it."

"What d'you mean, Jeremy?" asked Nick sharply.

"Can't you see, Nick? I thought Bastin had a trick up his sleeve. The mouth of the tunnel is barred."

For a moment no one spoke. All were staring at the mouth of the tunnel, then Nick whistled softly. "You're right, Jeremy. I see it, now. And, by the look of things, Bastin has done the trick properly. Grey metal, isn't it?"

Jeremy nodded. "Looks like it. I wonder where he got it?"

"Fetched it from the upper side, I expect." He paused. "Well, we've got to get through it. After all, we have the dynamite."

Jeremy shook his head. "That won't work, Nick. It's a hundred to one that the explosion would bring the whole roof down and block the tunnel. With your engineering knowledge you ought to realise that."

"I spoke without thinking," said Nick. "Of course you're right. We must have a look at it and see what can be done."

By this time the launch was close to the mouth of the tunnel, and they were all able to see the nature of the obstacle. It was a gate of grey metal similar to those which barred the entrances to the upper cave, and had been wedged into position in such a way as gave evidence of considerable engineering skill. Great rivets held it on one side, and on the other it was locked to a huge staple driven solidly into the rock.

"A pretty useful bit of work, considering in how short a time he had to do it," said Nick. "There is one thing about it, however. I don't suppose that it is charged. Well, there's nothing for it but to cut out the staple or the padlock, and happily we've got some files."

"It will be a longish job, won't it?" said Jeremy gravely.

"A good hour's work," agreed Nick. "But looking at it won't help. Some of you hold the launch up to the gate, and I'll get to it."

As he spoke he had already taken a file from a box under the stern sheets of the launch, and next moment had vigorously attacked the heavy staple.

Mort spoke aside to Jeremy. "I guess Bastin won't be very long," he whispered. "How'd it be if I was to climb up the bank and lay for him with my little gun?"

There was admiration in Jeremy's eyes as he looked at the plucky young American. "It's a topping good idea, Mort; only it's my job, not yours."

Mort flew into a regular rage. "What are you giving me?" he snapped. "I reckon a little fellow like me can shoot as well as you, even if you are six feet high. You got to use them big muscles of yours to help Nick to cut them bars."

Jeremy looked doubtful. It went against the grain to give up the post of danger to Mort, yet he could see that Mort had reason on his side. But just then something happened which abruptly ended the argument. Loud splashings sounded behind them, and high-pitched shrieks and screams rose above the whistlings of the gas fountain.

"Watch out!" shouted Jake in sudden alarm. "Heah's de whole bunch ob dem Bat Folk a-coming."

By the look of it, the coloured boy was not far wrong, for a flotilla of canoes was in sight racing up round the bend below.

Mort sprang for his pistol and Jake snatched up his crossbow, but Jeremy grabbed them both.

"No!" he cried. "No! Don't shoot. Can't you see they're scared stiff, and their one idea is to get away? Nick, drop that file and help me shift the launch out of the way."

Nick whirled round with a look of blank amazement on his face. "What are you talking about, Jeremy? You gone dotty?"

"Not that I know of," returned Jeremy calmly. "Can't you see that a mob like that will swamp the launch, and us, and everything if they once get round us? What's the matter with letting them have a chance at the gate? They're a fairly hefty lot, and among them they might make a job of it."

"Gad, you're right!" snapped Nick, as he leaped for the engine control and began backing away towards the left-hand bank. He was only just in time, for next moment the whole fleet of canoes came rushing up to the barrier.

When the dwarfs caught sight of the gate they seemed to go mad. They shrieked and screamed like a whole forest of monkeys, and, for the moment, all was crazy confusion among them.

"They're too scared. They won't do a thing," said Nick. The words were hardly out of his mouth before the sound of a third explosion came thundering up the cavern. It was heavier than the other two, and sent a great blast of air rushing like a gale around the mighty walls.

The sound seemed to drive the dwarfs quite mad, and a score or more of them flung themselves on the great gate, hauling and tearing at it like lunatics. Suddenly a fresh canoe, of which the steersman was a man taller than his fellows, and who wore a curious head-dress, came rushing up.

"A chief," said Nick. He was right, for the man, springing to his feet, went leaping across the massed canoes, until he reached the men who were struggling vainly at the gate. With amazing strength he pulled them backwards, at the same time shouting what were evidently instructions. In less than a minute he had produced order out of chaos.

"He knows what he's about," said Nick. "Watch him. That's a cold chisel he's got hold of. Yes, and a couple of hammer- men."

Nick was right. The chief himself held the chisel, while two brawny helpers swung the hammers, and at once chips of rock began to fly in every direction around the base of the staple.

"That'll do the trick," said Nick with quiet satisfaction. "It'll do it in half the time we could have done it with a file."

"Yes, we owe him one for that," agreed Jeremy. "The only question is whether the job will be finished before Bastin appears."

Nick's lips tightened. "It's going to be bad for Bastin if he turns up too soon," he remarked grimly. "I tell you straight, Jeremy, that I mean to shoot first and talk afterwards."

"I'll watch out for him," said Jeremy, "and I'll let you know the moment he shows up. I want you to keep your eyes on the gate and be ready to push through the moment it's down."

None of those in the boat is ever likely to forget the tense excitement of those next few minutes, while the hammers rang upon the chisel, and the chips of rock flew rattling in every direction.

Each moment they expected to see Bastin's canoe appear, and all were ready for battle the moment he showed up.

"Can't think what's become of him," growled Nick. "What do you think, Jeremy? Has he got caught in one of those explosions?"

"I'd like to think so," replied Jeremy. "It would be a bit too good to be true. Myself, I think it's the fog. It's getting as thick as soup, and I expect he's having the deuce of a time to find his way."

Jeremy was right about the fog, for by this time the air in this lower cavern was filled with mist so thick that it was impossible to see more than fifty feet in any direction. From out of the grey vapour came strange sounds—spittings and hissings—and now and then a heavy thud. It was no longer possible to see the blue glare of the gas flame.

Chalma's pretty face was pale and drawn. "I can hardly breathe," she whispered to Jeremy. "Shall we ever see Koom again?"

"Of course we shall," replied Jeremy reassuringly. "See, the dwarf men have nearly finished cutting out that staple. In a very few minutes they will have the gate down."

"They're sure some workers!" exclaimed Mort.

"They're scared stiff," said Nick. "And I don't know that I altogether blame them. It feels to me as if the big bust-up was coming pretty soon."

Strange quivers rocked the floor of the cave, and suddenly there came a crash like the bursting of a great shell.

"Snakes!" gasped Mort. "Was that the gas going out?"

"No," said Jeremy. "It was only a chunk falling from the roof."

A sharp snapping sound made them all look round. "The gate! It's down!" snapped Nick, and reached for the engine controls.

Jeremy stopped him. "Steady, Nick! We must let that mob go through first. If we got in among them, they'd jump aboard and swamp us."

The moment the staple holding the gate had been torn from its fastenings, a score of the dwarf men had flung themselves upon the gate itself and wrenched it down. It fell outwards with a crash, swamping two of the canoes and leaving their occupants struggling in the water. The rest, blind with panic, paid no attention to their drowning companions, but paddled away frantically into the darkness of the tunnel.

The narrow channel was crowded from wall to wall with the light, metal craft, their crews screaming and shrieking as each tried to drive ahead of the other.

"Bastin's a-coming," announced Jake suddenly. "I can sure hear paddles, down thar in de fog."

"He's right," said Jeremy. "Shove on, Nick, but go slow, and whatever you do, don't bump into that mob ahead."

The launch glided forward and drove into the black gloom of the tunnel. As she passed under the arch, Jeremy, looking back, saw the dim shape of a canoe coming up behind, but whether or no Bastin could see the launch, that he was unable to say.

Nick spoke. "Jeremy, it's as black as a hat, and I'm scared stiff of bumping into the wall. Dare we switch on the searchlight?"

"Not on your life, Nick. We should simply make ourselves a target for Bastin."

"A case of the devil and the deep sea," grumbled Nick.

"Keep her slow," begged Jeremy.

"You forget the current," Nick remonstrated. "As it is, I've barely steerage way."

The dwarfs were making such a din in front that it was impossible for those in the launch to hear the splash of Bastin's paddles or know whether or not he was gaining upon them. Jeremy felt certain that by this time Bastin was desperate enough to shoot them down instead of attempting to recapture them. He made Chalma lie flat in the bottom of the launch, while he himself, pistol in hand, strained eyes and ears in a vain attempt to detect the approach of Bastin's canoe.

There came a sudden shock, and, with a jar that made her tremble from stem to stern, the launch stopped. Nick fumbled vainly with the controls, but although the engine seemed to be still running, the launch lost way, and they felt her swing round with the stream.

"Your paddles! Get out your paddles!" snapped Nick. "We have hit a rock and smashed the screw."

Fortunately there were plenty of spare paddles. Four were got out, and once more the launch began to forge slowly ahead. But the launch, of course, was far heavier than Bastin's light canoe, and all four boys were well aware that their enemy must be gaining hand over fist. The suspense was almost unbearable, but they said nothing—only paddled with all their might.

So several minutes passed, until suddenly Jake gave a smothered cry. "Dere's light, I sure see light."

"So do I," said Nick hoarsely. "Paddle, all of you, they are the lights of Koom."

Hope gave them fresh strength, and the launch drove on at such speed that within a couple of minutes she was flying out under the upper arch into the Cave of Koom.

"Dem lights!" exclaimed little Jake. "I nebber thought I'd see dem lovely lights again."

Bang! From out of the tunnel behind them came the crashing report of an automatic, and a bullet whizzled overhead.

"Get to the bank," said Jeremy breathlessly, and with a powerful sweep of his paddle, he forced the launch in close to the left-hand shore. Springing to his feet, he made a great leap and gained a ledge of rock. "Paddle on," he cried to the others. "I'll settle with Bastin." As he spoke he picked up a great stone, and carrying it, went scrambling rapidly towards the top of the bank.

"Watch out, Marse Jeremy," shrieked Jake. His warning was too late, for at that moment Bastin's canoe came flashing up out of the tunnel mouth, with Bastin himself crouching in the bow, his pistol in his hand.

Jeremy had just reached the top of the bank, and was in the act of lifting his stone to hurl it down upon the canoe, when Bastin pulled his trigger. They all saw Jeremy spin round, drop his stone, and fall full length into a patch of scrub. Next second Jake had made one wild leap out of the launch and reached the ledge, while Nick, snatching up a pistol, turned to fire at Bastin.

"Better not," came Bastin's voice, cold and cruel as sin. "I have you covered, and if you fire, you will share the fate of your companion. What is more, it is not you only who will suffer, but also your friends. In the past I have been too merciful; it is a mistake I shall not make a second time. If you wish to save Phra's daughter, you will lower that pistol, Mr. Prest."

Nick saw the pistol pointing straight at his chest, and watched the evil face of Kasim as he stood behind his master, also armed. For himself, he cared nothing, and if by the sacrifice of his own life he could have saved the others he would not have hesitated for a moment. But Jeremy was dead, and he alone stood between Chalma and the vengeance of these scoundrels. With a groan he lowered his pistol and stood still and silent.

"That is better," remarked Bastin. "I thought that you would see reason. Keep quite still, please, and kindly remember that you are covered both by Kasim and myself. Also, you will order that negro boy to remain where he is."

Nick turned his head slightly to look at Jake. The coloured lad, instead of springing recklessly up the rock as Jeremy had done, was cleverly worming his way up through a crevasse in which he was hidden from Bastin.

"I can't stop him," said Nick curtly. "He is out of my reach as well as yours."

A perfectly fiendish expression crossed Bastin's face. "If you fail to stop him, you pay," he answered. "I shall shoot you dead if the boy shows on the top of the bank."

"You hear what he says, Jake?" said Nick.

"I hears, Marse Nick," replied Jake, and standing up, pushed his head above the rocks which shielded him.

Bastin turned his head slightly to glance at him, and as he did so there came from the stern of the launch a sharp twanging sound. A metal bolt struck Bastin between the eyes, and Nick, hardly able to believe his senses, saw the man reel backwards, fall against Kasim, and both go crashing together into the bottom of the canoe.

Quick as light, Nick's pistol was flashing and banging, and as the bullets ripped through the light metal of the canoe, her paddlers leaped overboard and swam madly towards the bank. The canoe itself swung round with the current, and began to drift backwards towards the opening from which it had so lately emerged.

"I told you I was hot stuff with a sling shot," remarked Mort, as he picked himself up from where he had been crouching in the stern-sheets of the launch.

"It was a wonderful shot," said Nick gravely. "I think you killed Bastin stone dead, Mort."

"And I guess you finished Kasim all right," replied Mort. "He hasn't moved, anyway."

"But Jeremy. They have killed Jeremy!" sobbed Chalma.

"He ain't dead. Tell de little lady Marse Jeremy ain't dead," came Jake's voice shrilly from the top of the bank.

"Let me go to him," cried Chalma.

"Bandages. Take the bandages," Nick told her, but she had them already as well as the precious flask of Kal.

Nick hesitated. He longed to go too, yet felt that he must not leave the launch, for the river above was still full of the canoes of the Owl Folk, who were now recovering from their panic. Glancing down-stream, he was just in time to see Bastin's canoe disappearing into the depths of the tunnel bearing its dead burden back into the Under-world.

Next moment he heard Jake's voice from the bank. "We stopped de bleeding, Marse Nick. Marse Jeremy, he's shot between de ribs, but de bullet has come out ob de back, and we's bandaging him up good and tight. Kin yo' come and help us get him down into de boat?"

"I'll have to stay by here," said Nick. "Mort, you and Flibberty, go and help Jake." By a sign or two Mort made Flibberty understand what was wanted, and Nick was left alone in the launch. At once he set himself to see whether anything could be done to repair the damage.

It took him, however, only a minute or two to find that the screw was hopelessly smashed. There was nothing for it but to paddle all the way back to Koom, and he had an uncomfortable feeling that the Night Folk would be apt to make trouble.

"Heah's Marse Jeremy," called Jake cheerfully, and Nick saw Jeremy, looking very white but extremely happy, being helped down the bank.

"My dear old chap," said Jeremy as Nick grasped his hand. "It's almost too good to be true."

"It's Mort we have to thank," Nick answered. "Are you badly damaged, old chap?"

"I've lost rather a lot of blood, but give me a week on my back, and I'll be as good as new. What about those Bat Folk, Nick? Are they going to turn ugly?"

"If they do, we still have a stick of dynamite," Nick answered grimly.

"Deys a-coming back," remarked Jake suddenly.

"So we're not out of the wood yet," grumbled Nick under his breath as he helped Jeremy to stretch himself comfortably in the bottom of the launch.

"They're not showing any slings or spears," said Jeremy, "so don't start shooting, Nick, unless you have to."

Several canoes were coming slowly back downstream, but, as Jeremy had said, their occupants were not showing any weapons. Flibberty, who, so far, had taken little part in the proceedings, began to make signs. He pointed first to his mouth, then to his stomach, and lastly to the dwarfs.

"Say," exclaimed Mort. "He means they're going to eat us."

"Ask Chalma," said Nick. "She'll know." Jeremy spoke to Chalma, who burst into a merry trill of laughter, a sound they had not heard for many days. Jeremy, too, laughed. "Don't worry, Mort," he said. "It's true they're hungry, but it's our grub, not ourselves, they're after."

Mort heaved a sigh of relief. "I guess they're welcome to it. With any luck, we ought to be home in time for dinner."

"All right," said Nick. "Hand it out to them, Mort. It isn't much, but it will keep them busy while we shove on up to the lake."

"I guess you better let Flibberty do the waiting," remarked Mort, as he took the remaining provisions out of the stern locker. "He knows their lingo."

There was no doubt about it. The wretched Owl Folk were literally starving. All their stores of provisions had been lost or left behind in the lower cave, and they fell upon what they were offered like hungry wolves.

"Tell 'em they shall have some more from the Pyramid, if they behave themselves," said Nick, and with Chalma's aid this message was given to the dwarfs.

"Time to push on," said Jeremy. "I'm afraid it is going to be pretty tough work for you people to paddle all the way to Koom. But I'm out of the running for the moment."

"Flibberty will take a hand," added Nick. "We shall manage all right."

As he spoke the air quivered, and from above came the thundering sound of the Mighty Voice. Chalma sprang up gleefully. "It is my father!" she exclaimed. "He has seen us. He is coming himself. He and Nath. He will meet us at the dam, if we can get that far."

"That'll save us a bit of bother," said Nick. "Come on, you fellows. All together, paddle!"

The dwarfs made no attempt to interfere, but falling in behind the launch, followed up to the dam. On the lake, at the far side of the dam, floated a good-sized launch manned by Phra and the old watcher, Nath. At sight of his daughter Phra leaped from the launch on to the dam, and next instant Chalma was in his arms. "My daughter! My daughter!" he cried. "Never thought I that I should see you again!"

"Nor would you, my father, but for the bravery of my dear friends," said Chalma.

Phra's usually grave face shone with happiness as he clasped the hands of each of Chalma's rescuers in turn. Even Flibberty was equally honoured. Mort vowed afterwards that the little Robot blushed, but, as Nick said, you might as well have expected a blush from a stone image.

They had to carry Jeremy across the dam, but with Phra's aid this was easy. Then they all packed into the other launch and Nick took charge. Chalma could hardly wait until they were settled before beginning her story.

When she came to how Nick had been deceived by Nartas and the Mighty Voice, a singularly grim expression came upon Phra's face. "We know," he said. "Never again will Nartas use that voice, or any other."

"You—you didn't kill him?" asked Chalma, horrified.

"No, my daughter, that evil man killed himself. Nath caught him, and in terror Nartas leaped from the window of the observatory."

Phra listened with breathless interest as she told of their adventures in the Outlands, nor did he speak again until she mentioned the choking of the lower tunnel and the flooding that followed. "Must it be then that Koom shall be drowned?" he asked gravely.

"It'll be real awkward if it is," said Mort, "for since Bastin chucked that rope of ours down the shaft I don't reckon there's any way out."

"Don't be an ass, Mort," said Nick bluntly. "You don't suppose Bastin left himself without some way of getting back."

"What do they say?" asked Phra, puzzled, and Chalma explained. Then his face cleared. "Trouble not your minds, my friends," he said, "There's another road, hidden and difficult, yet shown by our old charts. All here can safely reach the upper world, yet I know not how we of Koom shall find a livelihood in such changed surroundings."

Jeremy cut in, speaking Phra's own language, and explaining to him his reasons for believing that the water would escape before reaching the upper cave.

"It is likely that thou art right, my friend," said Phra, "but is it that thou and the others desire to leave us?"

"We must," replied Jeremy gently. "Remember, Phra, that our friends still await us in the Oasis of Feshan."

"But thou canst not go until thy wound is healed," said Phra.

"True, O chief, and gladly will I remain until I can walk again. But, with thy permission, two of us shall go up by the way of which thou hast spoken and take word to our friends that we still live."

Before anything else could be said the launch had entered the water gate and, as she did so, a mighty shout of welcome went up. To the amazement of the boys, the whole population of Koom was outside the Pyramid, lining the banks of the channel. Phra's face was a study. Even Chalma looked surprised. Then her merry laugh broke out.

"Father," she cried, "they have lost their fear. This is the beginning of new and happier days for all our people."

That night Phra gave a wonderful feast, a meal to which the boys, after their hardship of the past few days, did full justice. Even Jeremy, though on his back, had his share.

After the feast was over, Phra called Nick and Mort aside, and Chalma came, too, as interpreter. They talked for an hour, then Nick went to Jeremy's room. "It's all settled," he said. "Mort and I go to-morrow. Nath will guide us. If Professor Durham and Tuke are still in the oasis we shall find them, and I've promised Phra that we will not bring any one to Koom without his leave."

"But you haven't promised that you will not take a few things to Durham?" smiled Jeremy.

"I think," said Nick, "that I have enough to satisfy him and ourselves as well." As he spoke he put his hand into his jacket- pocket, and brought it out full of magnificent pearls.

Jeremy whistled softly. "Nick," he said "it's a fortune."

"Several fortunes, if you ask me," replied Nick dryly.

Jeremy, however, had one more visitor before he went to sleep. Nick had hardly left before Chalma slipped in. "They are going, Jeremy," she said quickly.

"But I'm not," smiled Jeremy. "You'll have to put up with me a little longer, princess."

"Must you go at all?" asked Chalma.

Jeremy stretched out a hand and took hers. "I must, princess. I cannot leave the others to find their way home alone."

She looked at him a moment in silence. "But you will come back, Jeremy?"

"I will come back," replied Jeremy gravely.


THE END