Fernando, bringing his rifle to his shoulder, fired a shot at random in the darkness. It was the last round they had. A laugh came back from the distance.

Without a word the guide put down his rifle on the ground and examined the wounded boy.

"He is stunned," said he. "He will recover presently."

So saying he lifted Harry in his arms and carried him a distance of about a hundred yards to a place where there was a small stream in the valley.

There he bathed the boy's face and hands, washing the blood from the wound in his ear. Presently Harry recovered consciousness, sat up, and looked about him.

"Where am I?" he asked.

It took but a word to remind him of what had happened, and then he remembered that he had held the Sunstone in his grasp. He looked up at Jim and smiled.

"I was so near to capturing it," said he.

"We'll get it yet, sir," answered Jim. "Just now I had the shock of my life. I thought you had been killed."

"I'm all right," answered Harry. "I feel dizzy; that's all."

In a little time he was able to continue on his way. The bullet wound in his ear was nothing; it was scarcely painful.

That night they camped in the mountains, intending to march at daybreak towards the British camp. When the sun rose, however, they found to their surprise that the whole column was already on the line of march, moving towards the east in pursuit of the retreating enemy.

When they reached the scene of the bivouac the camp-fires were still burning, but no sign of life remained.

The British column had vanished into the bush; and only a few hospital-wagons were to be seen trundling slowly southward.

In the centre of the deserted bivouac stood a tall solitary tree, and it was under this that they rested throughout the heat of the day. Fernando, who had been dozing, rose to his feet, stretched and yawned. As he did so he caught sight of a star-shaped cut in the bark of the tree, and on the instant it was as if the man had become transfigured.

His eyes lit up, his lips smiled. Amazement, delight, and infinite pleasure were stamped on every feature of his face.

"What is it?" asked Harry, at a loss to explain the man's behaviour.

"Heaven be praised!" he cried. "My brother is still alive!"

"Alive!"

"Yes. Cortes blazed that tree, and the blaze is not one day old. Last night he was here-in the midst of the British camp."

"Are you sure of it?" asked Braid.

"I know," Fernando answered with conviction. "In the days when we hunted together we sometimes lost one another in the bush, and on such occasions we blazed the trees along the tracks of bush elephants in just such a manner as this."

Harry Urquhart looked about him.

"There is no sign of Cortes here," he said. "He cannot have left with the British?"

"No," said Fernando. "He is hiding somewhere. Let me think, where would he go. Both he and I know this district well."

The man paused a moment, standing perfectly still. Then, on a sudden, with an exclamation, he set off running towards the hills.

He did not return until long after nightfall; and then it was with the joyful news that he had found his brother, sound asleep-beside three boxes of German ammunition.

Without delay, guided by Fernando, the whole party set off in haste. They found Cortes, sleeping heavily, in a little dried-up watercourse well screened by trees. It was characteristic of Fernando that he had not awakened his brother.

Harry bent down and touched the sleeper on the shoulder. The man sat up, rubbed his eyes, and then looked about him. The light of the moon fell full upon his face.

Harry grasped his hand and shook it warmly.

"You escaped?" he cried.

"Yes," said Cortes. "When we charged through the Germans, my foot struck against a boulder and I fell upon my face. I think the fall did some injury to my wound-the wound I had received from the Black Dog; for, when I tried to run, I found myself unable to do so.

"You were then some distance ahead of me," he continued. "I feared I would be overtaken. For a moment I knew not what to do. Then I came to a place where there was a great hole in the ground covered with bushes, and there I hid, allowing the Germans to pass.

"When they had gone, I got to my feet and tried to think matters out. I knew where my brother would take you; I knew he would go to the old fort. I might have rejoined you by way of the tunnel. I thought of doing so, but in the end I decided to go in search of ammunition, of which I thought you might possibly run short. British Government ammunition would be no good, as-with the exception of one Express-we have all got Mauser rifles. So three times I crept by night into the German camp, and each time returned with a box of ammunition. I secured also a haversack of revolver ammunition. Their sentries are sleepy dogs."

"You did splendidly!" cried Harry. "We are absolutely without a round."

"I knew you were in the fort," Cortes went on, "and I guessed you would go to the British camp. It was there that I blazed the tree whilst the troops were marching away. I returned to the hills, because I was tired and wished to sleep. If my brother found the blaze I knew he would follow me here."

The man smiled. He had every reason to be proud.

After a while the younger guide spoke again.

"The Black Dog still lives?" he asked.

Fernando bowed his head.

The following morning they began the final stage of their march towards the frontier of Maziriland. The route led them along the crest-line of the hills, and thence across a valley thick with undergrowth and jungle, where the heat was tropical and humid. They were glad to reach high ground once again, and set forward across the plateau beyond which the Maziri mountains stood up like a line of thrones.

These same mountains had been plainly visible from the old fort they had held so gallantly against the Germans, and had even appeared quite near at hand. But in these high altitudes the atmosphere was exceedingly clear, and, besides, the mountains were of great height, dominating the surrounding country far into the interior of the Cameroons.

It took them in all six more days to reach the frontier, when once again they found themselves in the midst of hidden dangers.

They had no idea of what manner of reception they would receive from the Maziris themselves; indeed, concerning this strange race very little is known, either to anthropologists or explorers.

It is generally supposed that the Maziris are a race that emigrated from north-eastern Africa very early in the known history of the world. Their features are aquiline, their lips thin, and the colour of their skin no more than brown. Not only are they certainly not a Negroid race, but they do not appear to have intermarried with the neighbouring Negro tribes in the Cameroons. It is possible they are direct descendants of the ancient Egyptians, though it must remain a mystery how they brought to the wilds of Western Africa the religion and traditional customs of the followers of Zoroaster.

As soon as they had crossed the frontier, Cortes and Fernando guided the party towards the west, in which direction were the caves. This also was the most deserted part of the country, nearly all the Maziri villages being towards the east, where the country was more fertile and suitable for pasture.

There is to be found in a certain part of Africa-far from the sites of the famous cities of the Pharaohs-indisputable evidence of an extremely ancient civilization. Even so far south as Mashonaland, are ruins of towns which could only have been originally constructed by highly civilized peoples. Ancient Egyptian history, the writings of the Greek historian Herodotus, as well as the Old Testament itself, place it beyond all doubt that the Egyptians, the Persians and Phoenicians spread their learning and their influence far into the interior of what, until only a few years ago, was the Dark Continent-unexplored, unmapped and quite unknown. It can only be supposed that Maziriland was a relic of the early civilization of the East, in much the same way as the inhabitants of northern Spain are distantly related to the Irish.

Before we enter this strange, mysterious country, it must be placed on record that there befell a certain tragedy. In a word, Peter Klein, having contracted a fever in the jungle, and, being much weakened in constitution by the nerve-strain and the hardships he had undergone, fell into a rapid decline-and died, as he had lived, pleading to be spared.

His companions buried him one evening among the rock-strewn, lonely mountains, and he goes out of this story as he came into it-a poor, mean object, a man of no account.

As for our four adventurers, daylight the next morning found them once more upon the hill-tops, shrouded in the mists. For fear of the Maziris the guides led the party by a roundabout way, giving the valleys, and even the lower mountain slopes, a wide berth; for there they were more likely to fall in with parties of the inhabitants.

On the next day, from the far south, there came a noise like thunder that continued until the afternoon. Hour by hour the British guns spoke in the distance. The Germans were being hounded from the Cameroons.

Day by day, as they continued their journey, the firing was repeated, growing fainter and more distant as they advanced. On the fifth day after Klein's death, they turned towards the north-west, and that evening crossed a valley. Beyond was a grass-covered plateau where wild asses grazed. The plateau dropped suddenly in a sheer wall of cliff, and they were obliged to walk many miles to find a place where they could descend.

At length they reached a mountain-top. Immediately opposite was another mountain, up which there was a path leading to a flight of steps. The steps ended suddenly in a black, yawning hole in the mountain-side. So far as the inhabitants were concerned the country appeared absolutely deserted. It was a barren inhospitable waste.

"Have we much farther to go?" asked Harry, turning to the elder guide. "Tell me, in which direction are the caves?"

"Yonder," said Fernando, pointing to the black hole in the mountain slope. "Yonder are the Caves of Zoroaster. There lies the treasure which the Black Dog and von Hardenberg have come all these thousands of miles to gain."

In single file, Cortes leading the way, they descended towards the valley.

CHAPTER XXV-The Lock

The Caves of Zoroaster are one of the most remarkable examples of the industry of the Ancients that are known to exist. As we have said, in various parts of the world, especially in the continent of Asia, there are many standing proofs of an advanced stage of civilization many centuries before the Christian era.

There are the catacombs in Upper Egypt-a labyrinth of subterranean passages extending for miles; there are the Pyramids, the Great Wall of China, the hanging gardens of Babylon-all of which are colossal and eternal monuments of the labour, energy and genius of the past.

The Caves of Zoroaster are perhaps as marvellous as any of these. Indeed, it is much to be wondered at that they were not included in the seven wonders of the ancient world. Time has not served to deface their majestic beauty, to detract from the solemn magnificence of these great vaults fashioned by human labour out of the living and everlasting rock.

Soon after our travellers had caught their first glimpse of the entrance to the caves, they decided to camp on the lower slopes of the mountain, for it was already growing dark. It would take them several hours to cross the valley, and they could not hope to accomplish the journey in the darkness. They accordingly retired to a place where there was a great hollow among the rocks, and here they deemed it safe to light a fire and cook their evening meal.

The following morning Harry awoke at daybreak. He was anxious to push on without loss of time. There was no knowing where von Hardenberg and the sheikh were. Perhaps they had already gained the caves.

As soon as they had breakfasted, Harry and his party continued on their way. The two boys, led by the guides, crossed the valley and then ascended the mountain opposite by way of a bridle-path, worn smooth by the feet of pilgrims. Throughout the ages, devout men had journeyed to the caves from the deserts of northern Africa and Arabia-by way of the caravan routes that extend in all directions across these arid wastes.

The path grew steeper as they approached the entrance to the caves, and presently they found themselves at the foot of a flight of steps. A heavy mist still wrapped the mountain in a kind of shroud. The steps ascended, one above the other, into the very heart of the mist which completely obscured the entrance.

These steps were like "Jacob's Ladder", mounting, as it seemed, to the very zenith of the heavens; and on either side of them, as far as Harry could see, were ranged strange statues-of lions with eagles' wings, of men with the heads of foxes, and great dragons that lay crouching like watch-dogs, guarding the treasure that lay beyond. All were graven in the same rough mountain stone.

For centuries the lightning had played upon the rocks about them, the hail and the rain had lashed these mute, immobile sentinels, so that in many cases they were broken and corroded like the gargoyles on a Norman church.

To mount that flight of nearly a thousand steps in the mists of morning, between these weird and hideous images, was an experience that bordered on the uncanny. On every hand a mighty stillness reigned in the heart of the mountains.

Indeed, it was as if this wild, forgotten country was some colossal graveyard of the past, where the wisdom of the Medes and Persians lay buried to the end of time, where the rugged mountain-tops stood forth like tombstones, piercing the very clouds.

At last they came to the entrance. The steps widened and they stood upon a great stone terrace, level as a table-top, on the farther side of which arose the side of the mountain, formidably smooth and perpendicular, the moisture on its surface glistening in the sunlight that struggled through the mist. It was like a wall of polished steel.

The entrance to the caves was wide enough to allow four men to pass abreast, and about ten feet in height. Black as Erebus it yawned in the savage cliff. On either side, carved in stone, protruding from the rock, were the figures of two enormous giants, armless, with great beards that extended to their waists, and those huge conical helmets on their heads which one has learnt to associate with the Persians, the Assyrians, and the Medes.

Fernando walked to the threshold of the entrance and then turned sharp to Harry.

"I am a Spaniard," said he, "and the Spanish are a superstitious race-at least, that is how you would express it. Some speak of superstition, others of prescience-or foreknowledge of coming events. Call it what you like, I have the sense of a calamity impending. I am quite sure of that."

"How do you mean?" asked Harry.

"It is like this," Fernando went on; "we have come to a tragedy. The curtain is about to be raised."

"Do you fear to enter the caves?"

"No. But I will not go first. Lead, if you like, I am quite prepared to follow."

This was a new trait in the character of the half-caste. He had never shown fear or hesitation before.

Harry turned to Jim.

"Come," said he, and led the way beneath the darkened archway. Cortes and Fernando followed at their heels.

But Harry Urquhart had not taken ten paces forward when he stood transfixed in wonderment at the solemn magnificence and beauty of the Caves of Zoroaster.

The place was like a great cathedral. It was divided into three aisles by two lines of pillars. These pillars were extraordinarily massive. They had not been built up from the floor to the ceiling, but were part of the living rock, joining the roof to the floor. In other words, the aisles had been hollowed out by human labour, and the rounded pillars left at regular intervals to support the immense weight above.

The cave was lighted from above by several shafts that pierced the mountain, and which threw convergent beams of light across the shadows. Giving upon each of the side aisles were three doors constructed of wood, but barred with iron and studded with scores of nails. Above these doors, around three sides of the cave, was a kind of gallery, connected with the roof by a series of smaller and more frequent pillars.

At the far end, upon an altar, a single oil-lamp was burning. Behind the altar, and about twenty paces distant, was a wall of rock which immediately attracted the attention of the boys.

This rock was rough, as in its natural state, whereas elsewhere in the cave-on the floor, the ceiling, and the pillars-the rock was so smooth that it resembled masonry. Moreover, the aisles were of grey limestone; but the rock behind the altar was of red granite, in which the quartz and mica crystals glittered in the flickering light of the lamp.

By the side of the granite rock was something which Harry Urquhart recognized at once. On a single axis, supported at each end by grooves cut in the pillars, were nine enormous wheels of bronze. On the outside-or what would correspond to the "tyres" – of each of these wheels, were hundreds of strange cuneiform characters.

There was no doubt that beyond the red granite rock lay the vault which contained the treasure, and these wheels composed the Bramah lock by sole means of which the vault itself could be opened.

But without the Sunstone the wheels were useless. On the obverse side of the Sunstone was the explanation, or solution, of the riddle.

Harry walked up to the great bronze wheels and turned them at random, first this way and then that. Each revolved independently of the others, and could be turned either backwards or forwards.

From what his uncle had told him, he knew that each wheel must be turned until the characters visible along a given line corresponded to those upon the Sunstone. There could be no doubt as to where this line was, for, across the wheels, at about the height of a man's eyes, a bar of gold extended.

Whilst Harry and Jim were examining the wheels, Cortes was exploring the side aisles beneath the gallery. Presently he came towards his companions on tiptoe, with a finger raised to his lips.

"Come here!" said he in a whisper, beckoning to Harry.

Harry did so, and was conducted to one of the iron-bound doors, where the guide motioned him to stoop down and listen.

With his ear to the door, Urquhart could hear nothing for some seconds. Then there came to his ears a sound that was unearthly.

It was a low, continuous, moaning sound, like the howl of a dog in the distance. It grew louder gradually until at last it was close at hand, on the other side of the door.

There was something in the vastness of the place, in its stillness and its gloom, that was at once depressing and alarming. Harry Urquhart felt that he was rapidly losing confidence in himself. The great flight of steps without, the stone statues, the two carved giants at the entrance, the shadowy vault of the cave, pierced by shafts of light, and the solitary burning lamp-all these were mystical and weird.

The boy was well able to face danger, to take his life in his hands, but here he was confronted by what was suggestive of the supernatural. A feeling of fear possessed him-he knew not why. He drew back, shuddering, and turned quickly to the guide.

"Someone is coming!" he whispered.

At that moment there came a loud rapping on the other side of the door, which shook and trembled under the blows of someone who seemed like a maniac. They heard a bolt drawn sharply back. And then a voice let out a kind of shriek that ended quite abruptly. As one man, they turned and fled without shame or hesitation.

CHAPTER XXVI-The White Madman

They ran in all haste towards the entrance to the cave. The two guides led the way. If the boys were alarmed, the men were even more so.

The brothers had proved that they did not mind danger in the ordinary acceptation of the term, but, in their thinking, in this place they trespassed upon the precincts of the other world.

Cortes was about to make his escape to the terrace outside the entrance, when Harry called him back.

"Here!" cried the boy. "This way!"

In the semi-darkness he had caught sight of a narrow flight of stone steps which led to the gallery above. He was not so frightened that he had not a natural curiosity to see who approached on the other side of the door.

All this time a noise continued that echoed ceaselessly in the vastness of the cave. It was a noise of bolts withdrawn, chains jangling, locks unfastened, whilst a voice that was hardly human was continuously uplifted in a long, plaintive moan.

In the semi-darkness of the gallery the four trespassers knelt down, hiding behind the pillars in such position that they could see into the central aisle below. Their eyes were fixed upon the door whence issued these strange, uncanny sounds.

Presently the door opened, and there came forth into the light of the lamp the most extraordinary apparition it had ever been the lot of any one of them to see.

It was a madman. Moreover, one who was terrible in his madness. He was of a great age, for the hair of his beard and of his head was white as snow. And yet he was very tall of stature, and had the appearance of a man of colossal strength.

He was clothed in rags-rags which hung together by mere threads, so that his dark skin was visible upon his arms and back. The hair of his head was so long that it reached to his waist, a great beard spread over his chest. At his side he carried an enormous sword-a two-handed sword such as was used by warriors in ancient days. In one hand he held a staff.

He came forward, singing a wild song that somehow was reminiscent of the desert and the East. He approached the altar where burned the lamp, and there flung himself upon the ground, tearing his hair, gnashing his teeth, and actually foaming at the mouth.

From time to time he lifted his voice in a howl, dismal and prolonged, breaking off in his singing to beat himself upon the chest. It was all terrible to behold. It was like a scene in some majestic Bedlam. This white madman, the semi-darkness of the cave, the flickering light, the enormous pillars-all seemed not of the world we know, but to belong rather to one of the worlds of which we sometimes dream.

Harry, turning to Fernando, whispered in his ear.

"Who is this man?" said he.

"He is Guardian of the Cave. He is said to be a hundred years of age. He has lived here all his life."

The old man rose to his feet and stretched forth his arms. Then, lifting his voice, he uttered an endless string of words that were incomprehensible to both boys. As far as Harry could make out, the man either uttered some fearful curse or else he prayed in anguish.

"What is he saying?" asked the boy.

"I am not sure," answered Fernando; "I know little of the Maziri language. I think he says that the Sunstone has been stolen these many years, but this very day it will return. He says the vault will be opened before nightfall. He says that he himself is about to die."

"How does he pretend to know these things?"

"I cannot say," said the guide. "These men have the wisdom of the ancients, who could read the stars and knew of many things long since forgotten. It is supposed by the Maziris themselves that by means of fasting and penance and self-inflicted torture he has gained such holiness that he can see into the future, that he can read from the Book of Fate."

They could not move their eyes from the Guardian of the Cave. He now stood erect and motionless before the altar like one transfigured into a kind of deity. There was little about him that suggested what we know as human.

He was straight of back, his bare arms folded upon his chest, his head a little lowered. And the shafts of daylight from either side of the cave converged upon the whiteness of his head, so that he was like a saint, solemn and magnificent, surrounded by the all-pervading gloom.

Suddenly he let out a shout that was half a shriek-louder than before; and then they saw that his madness was not feigned. Like a wild beast he hurled himself upon the wheels and set them all in motion, some revolving one way, some the other. And even as the wheels were turning he shook his fist at the entrance to the vault-the red granite rock at the extremity of the cave.

"Open!" he cried, in the strange Maziri language. "Open in the name of Zoroaster!"

Again and again, he cried to the vault to open, as though that which was inanimate would heed his infuriated words. The spokes of the great bronze wheels reflected the light from the lamp, but there came no answer to the man's cries but the echoes of his own voice in the dimness of the cavern.

Once again he flung himself upon the ground, and prayed in a loud voice that the spirit of Zoroaster might descend and show him how to open the vault. According to Fernando, he asked the gods to grant him one of two favours-either that the secret of the Sunstone might be conveyed to him then and there, or that the Sunstone itself might be returned to the cave.

And suddenly he stopped in the midst of his prayer, springing sharply to his feet. For some seconds he stood quite motionless, in the attitude of one who listens.

Then he spoke slowly and distinctly and less loudly than before.

"My prayer has been heard," said he. "Glory to Zoroaster!"

At that he lifted a hand to an ear and turned his head towards the entrance to the cave.

Those in the gallery listened, too. Sure enough, footsteps were approaching.

A little after, the daylight at the entrance was obscured by a figure-the figure of a tall and slender man dressed in the clothes of a European. For a moment he stood quite motionless, shading his eyes with a hand.

It was apparent that, newly come from the daylight, the new-comer was unable to see in the half-light of the cavern. Neither could he himself be recognized by those in the gallery.

Presently he came forward until he stood before the Guardian of the Cave, and the light from the burning lamp fell full upon his face.

Harry Urquhart caught his breath, and his hand went quickly to the handle of his revolver, when he recognized von Hardenberg, who had come to his journey's end.