They waited for many minutes in absolute silence. Peter Klein was seated at the fire. There also was Fernando, who appeared to have fallen asleep in a sitting position. As for the two boys, they remained near the opening through which the man had passed, straining their ears to catch the slightest sound without.

Presently there came the sharp report of a shot. Then all was silent again.

Fernando immediately sprang to his feet and walked towards the boys. He must have been sleeping lightly, or else feigning slumber.

"My brother," said he, "is dead."

"Dead!"

Both Harry and Braid uttered the word in a single breath.

"That," said the man, "was the rifle of the sheikh."

"How do you know?" asked Harry.

"For a very simple reason," said the other. "There were two reports, therefore the shot was fired in this direction. If a man fires away from you, you hear but one report, which is like the crack of a whip. But if he fires toward you, you hear two reports, each one of which resembles the 'pop' of a cork. The shot was fired this way. The trigger was pressed by the Black Dog, whose bullet seldom misses its mark. Therefore, in all probability, my brother is gone."

"And you speak of it so calmly!" uttered Braid.

Fernando smiled. "With us who live on the Coast," said he, "death is an easy matter. Sooner or later we all die; some by murder, some by malaria, some by Black Jack, which is the most deadly fever in the world. Our graves are in the bush. What does it matter whether or not a bullet finds its mark?"

The two boys were astonished. They could not understand this strange man's views of life and death.

"And you have sacrificed your brother's life," asked Harry, "merely to prove that the Black Dog of the Cameroons intended to murder Klein?"

Fernando shook his head.

"I would have gone myself," he answered, "had that been possible. As it is, I can live, at least, for revenge."

The full significance of the thing burst upon Harry Urquhart.

"A wasted life!" he cried.

"Oh no!" said the man; "a life is never wasted-for the truth."

After that they were silent; they remained standing close together by the opening in the wall. Harry felt as if a heavy weight had been placed upon his heart.

Without, through the fissures in the wall, they could see the moonshine and the stars. A soft wind which moaned across the desolate and rugged heights was blowing upon the mountain.

Presently they were startled by the sound of a voice-a voice that spoke in a whisper.

"I am wounded," said the voice, "I am wounded almost to death. Fernando, my brother, hold out a hand to me, that I may speak to you before I die."

Harry was about to move to the opening, when the elder guide fiercely thrust him back.

"Do you suffer great pain?" asked Fernando, speaking tenderly, as he approached the fissure on tiptoe.

"Give me your hand," came the answer in a weak, breathless voice.

Instead of a hand, suddenly Fernando thrust his rifle through the opening and fired. The loud report echoed in the shallow vault. A strong smell of cordite was driven to their nostrils.

Without, there was a shriek. Harry rushed to the opening and looked through. He saw a white figure flying in the moonlight like a ghost. Fernando-the half-bred Spaniard-threw back his head and laughed the laugh of a fiend.

"What does all this mean?" cried Braid, turning fiercely upon the man.

"That was no more my brother," said the guide, "than the dog-fox is brother to the eagle. That man was the sheikh-the Black Dog himself."

"It was your brother's voice," said Harry.

"Indeed!" said the man. "I should know my brother's voice. I tell you once again my brother is dead. The Black Dog slew him; and then, recognizing the man he had killed, he guessed that I, too, was with you, and he came here to kill me, imitating my brother's voice, practising the cunning which has made him feared from the Niger to the Congo. And he has gone with a bullet in his chest."

"You did not kill him?" asked Braid.

"No. He fled, realizing that his trick had failed. But because he killed my brother, Cortes, whom I love, I swear now by the saints that I will avenge my brother's death, that I will send the Black Dog to the shades. Henceforward it is his rifle against mine, his treachery against my wits; it is the fox against the serpent."

All this time they had forgotten something of superlative importance. When events of startling magnitude occur in such quick succession it sometimes happens that the obvious is overlooked. And strange to relate, it was Peter Klein-who hitherto had seemed quite incapable of thinking for himself-who was the first to realize the exceeding gravity of their situation. On a sudden he rushed at Fernando like a maniac, and seized him by the arm.

"You say," he cried, "you are sure your brother is dead?"

The man bowed his head.

"Then, if he is dead, by Heaven, we are buried alive!"

CHAPTER XV-The Valley of the Shadow

The truth came upon them all in the nature of a shock. They could not think how it was that they had overlooked so simple a deduction, so obvious a fact.

Cortes, by reason of the extreme slimness of his form, was the only one of their number who could manage to squeeze himself through the narrow opening. The stone above the circular hole in the roof, or ceiling, could not be moved from the inside. The hiding-place that they had deemed so secure a refuge was nothing but a death-trap.

Peter Klein turned in anger upon the guide.

"So much for your wisdom," he cried, "so much for your oath!"

The man's eyes flashed. His hand went to the knife he carried in his belt. One half of him was a savage, and the other half a Spaniard.

"Do you think," said he, "that I thought my brother would be killed?"

"So far as I can see," said Klein, "it is all the same to you."

"There you prove yourself a fool," answered the other hotly. "You think I do not love him because I do not weep like a woman and gnash my teeth. Understand this-the heart of a Spaniard is like a deep pool, the surface of which is still. We feel; we love. Also, I warn you again, we can hate."

The spy dared not face the man's blazing eyes.

"I warn you," Fernando went on, his voice rising as passion swayed him, "if you hold me up to ridicule, you die. I am ready enough to admit that my judgment was at fault-that I forgot that, without my brother, we were unable to leave the cave-but to be put to scorn by such as you is more than I will endure!"

Peter Klein fell back before the fiery onslaught of the man's words as though he had been struck. The half-caste stood upright, every muscle taut, his eyes ablaze, his clenched teeth showing in the blackness of his long moustache. Then he hurled his knife upon the floor.

"Why do I waste words upon such as you?" he cried, as if in anguish. "You are not worthy of my anger!"

"I cannot yet understand," said Harry. "If the sheikh is so formidable an adversary, why did you send your brother into the night dressed in Klein's clothes?"

"I spoke high words of the prowess of the Black Dog," said Fernando, "but all the time I believed in my brother. Cortes was a fine shot, second only to the sheikh himself. Moreover, he was agile, one of the finest stalkers who ever lived. I knew, when I was sitting by the fire, that we would soon hear a shot. You thought that I was sleeping, but I was praying to the Holy Virgin that the first shot would be fired by my brother, and that the Black Dog would lie in his own blood, his life ended, the Book of Fate closed upon his evil deeds. When I heard the double report, my heart sank within me. I knew that my brother had been outwitted-that the victory lay with the sheikh."

"And in the meantime," said Harry, "we are buried alive!"

"The fault is mine," said the guide. "I should have asked my brother to remove the stone at the entrance before he went, in case of any mishap. I forgot to do so. I ask forgiveness."

"There is nothing to forgive," said the boy. "In such a country as this, encompassed upon every hand by death and dangers of all kinds, there are a thousand things to think of. I would be the last to blame you."

"You are generous," said the man. "The English, with all their faults, are the most generous race on earth; and because they are just, I honour them. We have food and water to last for some days. We can but put our trust in Providence."

Of the days that followed it is unnecessary to tell in detail. In the gallery, shut out from the outside world, from the pure air of the mountains and the sunlight, existence was a living death. For all that, it was wonderful for how long they retained their strength. Indeed, it is a remarkable fact that a man can go for many days with little food, if he has water to drink and is not asked to undergo great physical exertion. But at last Peter Klein grew so weak, and the beating of his heart so slow, that Harry feared he was dying.

It was during these days that the boys came to love the wizened half-caste in whose hands was their fate. Fernando's courage knew no bounds; it was as if his will-power was invincible. Never once did a word of despair or hopelessness leave his lips.

They longed for the open air, for freedom. Days and nights were all the same to them, except that sometimes the sunshine, sometimes the moonshine, invaded the depths of their prison through the great fissures in the wall. As time went on it was difficult not to give up hope.

At last, one night, Fernando rose to his feet and approached Harry, who found it impossible to sleep.

"My friend," said he, "the sands are running down, but I think that I can save you."

"How?" asked the other.

"Look at me!" cried the man. "I am little better than a skeleton. I think I can creep through the opening in the wall."

Assisted by Braid, he crawled to the fissure, and there endeavoured to pass through. It is true that he had wasted away terribly, but the opening was very narrow, and his frame was larger than his brother's.

For an hour he struggled vainly. At last, he gave it up.

"It is no good," said he. "I cannot do it. We are lost. Nothing remains but death."

They resigned themselves to their fate. They were far past all complaint. Even Klein was silent; he no longer moaned and deplored his unhappy lot. Even he had learnt to prepare himself for death.

Three more days passed, and at the end of that time Fernando himself lay upon the floor in a kind of faint.

It was bitterly cold. They had no fire. They had burned all their wood. Only a little water remained. The prospect before them was horrible to contemplate. They were destined to be driven mad by thirst.

For some time Harry walked backward and forward. Then fatigue overcame him, and, lying down upon the floor, he immediately fell asleep. When he awoke it was daylight. He went to the bucket of water to divide the little that remained into four equal parts. To his astonishment, he found that the bucket was empty.

He uttered a loud exclamation, which brought Braid to his elbow.

"What has happened?" asked Jim.

"Our last drop of water," said Harry, "has been stolen."

There was little doubt as to who was the thief. Neither Harry nor Jim nor Fernando could have been capable of such treachery. Harry turned fiercely upon Peter Klein.

"Do you deny this?" he asked.

"Yes," said Klein; "I do."

They examined his pannikin and found that the inside was wet. There was also a drop of water upon the floor by the place where he had been sitting. Without a doubt, during the earlier part of the night, the man had pretended to be asleep until the three others were buried in slumber. Then he had stolen all that remained of their water.

Fernando rose slowly to his feet, drew his long knife, and, tottering from weakness, approached the German spy.

"Death," said he, "is too good for you! But, weak as I am, you die!"

Harry held out his hand.

"Let him be," said he. "His cowardice will avail him little. He will only live to see us go before him. He has done no more than prolong the agony of his death!"

The guide returned, growling like a dog, and sat down upon the floor.

During that day hardly a word was spoken. They sat in silence, waiting for the end. Towards afternoon a raging thirst began to consume them; their blood grew hot in a kind of fever; their tongues clave to the roofs of their mouths.

And at nightfall they lay down to die. Fernando was now in a kind of stupor. For an hour he never moved, but lay like one already dead. Both Braid and Klein fell asleep, but Harry found sleep impossible.

Knowing that the end was drawing near, he resolved to commend his soul to the Almighty, and, burying his face in his hands, he began to pray.

For some minutes he prayed silently, making his peace with God. When his prayer was finished he felt happier. He sat for some time with his hands clasped about his knees, looking upward at the round stone which confined them in their prison.

And as he looked the stone moved as if by magic, silently. Through the round hole above, the light of the moon streamed down into the darkened vault.

CHAPTER XVI-The Enemy in Sight

For some moments Harry Urquhart did not move. He sat like a graven image, his eyes staring, his jaw dropped in amazement. Then the full truth burst upon him in a flood. He sprang to his feet, uttering a loud cry which immediately awoke both Braid and Peter Klein.

"What is it?" cried Braid. "What has happened?"

Harry seized his comrade by the shoulders and shook him violently.

"Tell me, Jim, have I gone mad, or has a miracle happened? Look there!"

Braid looked in the direction indicated, and saw, to his amazement, that their prison doors were opened, that the stone had been rolled away from the circular hole in the roof.

By that time Fernando had got to his feet. He came swaying towards them, and clutched hold of Jim's arm for support. Perhaps the climate of the Coast had weakened his constitution. At any rate, he was now far weaker than the others-even than Klein.

"We are saved!" he cried. "But beware of treachery. For all we know the Black Dog may be hiding at the entrance."

Harry cared nothing for that. A sense of freedom, a breath of mountain air, were worth all the risk in the world. He scrambled up, caught hold of the edge of the hole, and with great difficulty managed to pull himself through, so that he stood in the light of the stars, amid the mists that wrapped the mountain.

At his feet lay a still, dark form. It was that of a human being, but so motionless that the boy feared that it was that of a dead man. Going down upon his knees, he turned the body over, so that the face was uplifted to the moon; and at once he recognized the features of Cortes, the younger guide, who had gone out to slay the sheikh.

He spoke to the man, but received no answer. Then he rushed to a spring that was near by and quenched his burning thirst.

There he was joined by Jim Braid and Peter Klein. Both went down upon their knees at the spring-side to drink their fill.

After that they assisted the elder guide to escape from the terrible prison in which they had spent so many days. They sprinkled water upon the lips of the younger man, and at last he opened his eyes.

"We thought you dead," said Harry. "Tell us what happened to you?"

"I went my way, dressed in the clothes of that cur, to trick the Black Dog of the Cameroons. Knowing the man with whom I had to deal, I was cautious and on my guard.

"I approached so silently that not even a lizard could have taken alarm. Then I saw the man waiting for me on the mountain-side. He was dressed in his white Arab robes; he was seated on a boulder, with his rifle on his knees.

"I considered what was best to do. I had intended to show up at a distance, pretending that I was the German. Then I remembered that if the sheikh fired I would assuredly be hit. In the end I decided to creep upon him unawares, to snatch his rifle from his hands. With a man like the Black Dog it is best to strike the first blow, and also to strike hard.

"How he saw me I cannot say. His eyes are like those of a lynx. But he discovered me and fired, and I was wounded. The bullet pierced my chest. For a moment I think I was unconscious, for when I opened my eyes the sheikh himself was kneeling over me, looking into my face. He recognized me, and called me by my name.

"Without doubt he thought I was dying. Indeed, he left me to die. He went his way up the mountain. Presently I heard a shot, and a little after the Black Dog came past me, running as if for life. When he was quite close to me I saw that there was blood upon his robes and that he was running after the manner of one who suffers pain and is wounded. How that happened I do not know. At the time I thought little about it. I did not doubt that I myself stood at the door of death.

"I fainted, and when I recovered consciousness I was consumed by a terrible thirst. Fever raged in my bones. With great difficulty I managed to drag myself to the side of a spring, where I drank great draughts of water. After that I fell asleep; and for the next three days I lay in that place, thinking that I was dying, frequently drinking at the stream. I could not walk, for whenever I tried to rise to my feet there was a pain in my chest like a red-hot sword, and I came near to fainting.

"One night I thought of my brother and my friends, and then it was that I remembered that you were unable to escape from your prison.

"Ever since then I have been struggling up the side of the mountain, endeavouring to get to you to rescue you. Every minute I thought that I was dying; sometimes I was so weak that I felt I could go no farther. Yet every day I made a little progress. I followed the direction of the stream. I drank the water, and ate wild berries, as well as the provisions I carried with me.

"I reached the stone; I remember rolling it away, and after that I remember no more."

The narration of this story was too much for the man's strength. As he said the last words he fell backward in a faint.

For the rest of the night they camped in the open air, sleeping around a fire. They remained upon the mountain-top for four days. The German troops had evidently left the district, and though Harry and Jim hunted in the valley, and succeeded in shooting some guinea-fowl, they saw no signs of von Hardenberg and the sheikh, who had evidently pushed forward on their way towards Maziriland and the Caves of Zoroaster.

It is remarkable how quickly they were completely restored to health. Food and water and the freshness of the mountain air lent their assistance to Nature; and even Cortes, who had been so severely wounded, rapidly regained his strength. Indeed the wound was already healed, and all he required was nourishment and rest.

When they were able to continue their journey, they decided to advance with the greatest caution. A few miles farther on they would come to a long valley, two hundred miles in length, which led directly towards the frontier of Maziriland. Cortes knew of a path that ran along the crest-line of the mountains, whence they would be able to survey the surrounding country except such as was hidden by the density of the bush. If they followed this there would be small chance of their being taken by surprise, either by the Germans or von Hardenberg and the sheikh.

At first they marched by easy stages, in order not to overtax their strength. This part of the mountain was inhabited by a great number of rock-rabbits, many of which they were able to kill with sticks; and these rabbits soon found their way into the cooking-pot.

By degrees they made their daily marches longer. They were anxious to overtake Captain von Hardenberg and the Black Dog, who were evidently several miles in advance. Finally they marched by night, the guides taking a direct route by the stars.

Suddenly, one midnight, as they rounded a great spur of rock, they saw a small light, dim and twinkling in the distance like a star, far below them in the valley.

"Look there!" cried Harry, pointing ahead.

"Is it a camp-fire?" asked Braid, turning to the two guides, who stood together.

Both bowed their heads.

"It is a camp-fire," said Fernando. "It is the camp-fire of the Black Dog of the Cameroons."