What had become of Paul? What was the cause of his absence from the school? Had he heard of the decision come to by his Form, and instead of waiting to be expelled, had he left of his own accord? That was the view of Newall and others of the Fifth.

"About the best thing he could have done," said Parfitt. "It wasn't only the flag business, but there were other things in the background. The Black Book business has never been cleared up, you know."

Parfitt made this remark in his most significant manner, with uplifted eyebrows and a shrug of the shoulders.

"That's right. Kick a man when he's down," drawled Waterman. "Parfitt's better at a drop kick than any fellow I know."

The Third were just as much concerned over the disappearance of Moncrief, jun., as the Fifth were over the disappearance of Percival. Stanley was doubly anxious—anxious for Paul, anxious for his cousin.

Could they have gone away together? That was scarcely likely. They were hardly on speaking terms for one thing; and even if the idea of running away from Garside had suddenly come into Paul's head, it was not at all likely that he had induced Harry to run away with him. What, then, had happened?

While the school was thus anxiously awaiting news of the missing boys, we will try to explain what had really happened.

Paul knew that a meeting of his Form had been called, and that he and his doings were to be discussed, probably censured. When would the time arrive that he might take steps to defend himself? When would his lips be unsealed? How much longer would Mr. Moncrief keep him in suspense, and what had become of Zuker?

Unconsciously Paul had strayed from the school to the garden where Hibbert had, not so long since, fallen asleep—in the sleep that knows no waking. He sat for a long time under the tree, thinking of these things, with no one to disturb his thoughts, save the birds that fluttered around him as they used to flutter around Hibbert.

What had become of Hibbert's father? Again and again the question came to him, and he could not dismiss it from his thoughts. He thought of the strange circumstance under which he had last seen him—of that weird scene in the cave with the man Brockman. All that had happened at that interview was fixed indelibly on his memory. He could see Zuker tracing with his finger on the chart the passage of the Dutch to the Medway—could hear his voice as he described all that had happened as they broke the chain on the river and advanced on Upnor Castle. Then—then had followed the strange appearance of the master, and the still stranger interview between him and Zuker.

Was the cave still there? Often and often a strong desire had seized Paul to go there again, but he had resisted it. Now, however, as he thought of all that had happened on the evening he went there, the impulse grew so strong upon him that he could wrestle with it no longer. He must respond to its call.

So, as one under some mighty spell, Paul passed from the garden, and was soon on his way to Cranstead Common.

It was beginning to get dusk as he followed the trail along which he had once followed in the footsteps of Mr. Weevil. After travelling some time in the direction of the river, he came to the thickly-wooded part, where the master had disappeared.

Searching amongst the brambles, he found the curious division which marked the centre, and placing his hand beneath the bushes as before, he was not long in finding the ring that was attached to the circular opening. Raising it, he entered again the sloping tunnel cut in the sandstone.

Though he had only been in that tunnel once before, he had travelled along it so often in imagination since that it seemed to him he was on familiar ground. He had hesitated when he first entered it. He knew not whither it would lead him, what dangers might meet him on the way. He hesitated no longer. Still he walked cautiously, with his hands before him, like a blind man in the darkness, until it began to broaden. Once he thought he heard footsteps behind him, and he came to a sudden pause. Was some one really following him, or was it only the echo of his own footsteps?

He listened attentively, but could hear nothing. It was as silent as the tomb.

"My ears must have deceived me," he told himself, as he continued his way.

Presently he came to that part of the tunnel where a faint film of light penetrated into it, and again the fantastic shadows he had before seen seemed to menace him at every footstep he took. The cave, then, was not deserted. It was still inhabited by some one. Who? Zuker and Brockman—the same tenants as before, or had some one else come into possession?

Yes, there was the curtain, partly concealing the main entrance to the cave. To reach it, he crawled on hands and knees as before, and peered through the space between the curtain and the wall.

There was no anthracite fire burning this time. It was dimly lighted by one of the lamps suspended from the roof. There was no sign of life. The place seemed deserted.

Paul waited for a long time listening. No sound came from the cave. It was as silent as the tomb. But as he listened, he thought that he could again hear the sound of a light step behind him, coming along the path he had travelled.

Was it possible that some one else had entered the tunnel? Surely the master had not again followed unconsciously in his footsteps? Paul turned his head and listened, but it was as silent in that direction as the other.

"I'm getting as nervous as a kitten," he laughed to himself. "My ears have again deceived me."

No one appeared to be in the cave. Mr. Moncrief had said in his letter that he knew about Zuker's movements. Could it have been that he had been arrested? It was just possible. Anyhow, he would like to have a nearer view of the cave. There could be no danger, and if there were, it was worth the risk.

So Paul rose from his hiding-place behind the curtain, and stepped cautiously into the cave. The guns and cutlasses were still hanging on the wall, but the models and designs had gone, and the photographic camera had gone from its niche.

There was a passage on the other side of the chamber similar to the one through which he had come.

"Where does that lead to, I wonder?" thought Paul.

There could be no harm in exploring it a little way. He might just as well know where it led to, if it were possible to find out. The information might be useful. Paul was animated with the adventurous spirit of the explorer, which knows no rest until it is satisfied. He crossed to the opening. At the moment he reached it, a figure emerged from the darkness, and confronted him. It was Zuker.

It was so sudden, so unexpected, that Paul could not move. He stood there as one rooted to the spot. Before he could move, the man had sprung upon him with the swiftness of a tiger, and seizing him by the throat, dragged him to the light.

"You!" he cried. "The boy from Garside. Your name is——"

"Paul Percival," gasped Paul, as the fierce grip relaxed.

"Paul Percival. Ach Himmel! It is Fate itself."

He had in turn shrunk back, as though Paul were no longer a being of flesh and blood, but a phantom. Then he murmured hoarsely to himself: "Weevil was right. The hand of a Higher than man is in it."

In the uncertain light he had not at first recognized Paul; but now he saw him, and knew that just as he had once been face to face with the father at a supreme crisis in his life, now he was face to face with the son. Had Paul seized that moment of stupefaction, he might have escaped, but he made no effort. And the moment passed.

"Who showed you this place? Who brought you here?" demanded Zuker, himself again.

"No one; I found it out myself."

"How?"

"That is my secret."

Zuker's hand went to his breast, to a weapon concealed there.

"Be careful how you answer, boy. You're not now in school, and you haven't a school-master to deal with. Is this the first time you've been here?"

"No."

Zuker started in spite of himself.

"Not the first time! How many times have you been here before then, may I ask?"

"Once."

"Ach! Now I understand. It is through you my plans have been defeated. It is through you my man—mein Brockman—has been arrested. It is through you that I have scarcely dared venture from this hole for two days past. You have been a mean, dirty spy."

"As you were to my father when I was a child." The words were upon Paul's lips, but he forced them back. Then aloud, "I've not been a spy. I've told no one."

Zuker looked searchingly into Paul's face.

"Who has told, then—who has given information to the police, to what is called your Secret Investigation Department—if it is not you?"

Paul was silent. He now understood Mr. Moncrief's letter. It must have been Mr. Weevil who had given information to Mr. Moncrief, it must have been he who had kept him informed of Zuker's doings. Mr. Weevil was not a traitor to his country, after all. Nay, it seemed as though he had striven, in his peculiar way, to defend it against traitors.

"Silent, eh? I can see what you've told me is false. You have worked against me from the first. It was you who outwitted me once before. It was you who got that packet through to the man who has always stood between me and my plans, the Admiralty man, Moncrief. All would have been over; I should have got all through had it not been for that. Ach Himmel, you will not have the chance of blabbing any more secrets! I have you now—tight in the Fox's Hole—and you will not leave it alive. Let me see what your school is good for. I will give you five minutes to get ready for sterblichkeit. Ach, it is a long word! Do you know what it means?"

Paul knew what it meant. It was the German word for mortality.

"Thank you," answered Paul simply. "That is longer than my father had when he was called upon to die, and it should be enough for me."

Zuker's hand trembled as it fingered the weapon concealed in his breast. Paul closed his eyes, and repeated in a low, yet clear voice:

"'Our Father, which art in Heaven, hallowed be Thy name. Thy Kingdom come. Thy will be done on earth, as it is in Heaven. Give us this day our daily bread. And forgive us our trespasses, as we forgive them that trespass against us——"

"Halt! Stop!" cried Zuker hoarsely. "You spoke of your father just now—how he died. Tell me quickly how it was."

"He was drowned, in saving the life of a man who had robbed him."

"Ach! And do you know who that man was?"

No answer came from Paul's lips for several seconds, seconds that seemed as hours. Deep silence reigned in the cave, then it was broken by the clear voice of the boy:

"Yes; I know who that man was. He called himself Israel Zuker."

Zuker could not repress a movement of astonishment as Paul pronounced his name.

"Knowing this—knowing that it was through me your father lost his life, you could yet say that prayer—'As we forgive them that trespass against us'? You are as brave as your father was," came hoarsely from his lips.

"I could wish no greater praise than that," answered Paul. "But I had not finished. Shall I go on?"

"You need not be in so great a hurry. Wait till I tell you. I have one or two more questions to ask you. How did you come to know that I was the man who spied upon your father—the man through whom he lost his life—the man——Ach!" He stopped himself suddenly. His brow darkened; the veins stood out in knots upon his forehead. "Fool! Why didn't I guess it? I see it all now. It is your master—it is Weevil who told you. It is Weevil who has betrayed me."

His hand went to the weapon in his breast again.

"No, you are mistaken; Mr. Weevil has told me nothing. He has not betrayed you."

"You are telling me false. You are trying to mislead me. Beware! No one else knew my secret. Who else could tell you?"

"I learned it from a little fellow whom I loved as a brother, and who loved me as a brother, too. Alas, he is now dead! We called him Hibbert."

"Hibbert—my son!" Zuker's voice softened wonderfully as the words passed his lips; then it hardened again, as he demanded: "How was it my son came to betray me?"

"It was after that accident on the river. Perhaps you have forgotten? It was I who helped him back to the school. And the dear little chap was always so grateful for it—always made such an awful fuss about it. That was his way—ever so much too sensitive and grateful. Poor little chap!"

Paul brushed the back of his hand quickly across his eyes; and somehow the man did the same.

"Well, I was often with him after that," he presently continued. "He felt that he would never get well, I think, and I could see that he suffered a good deal from something he had on his mind. I never guessed what it was; but one night, when I was sitting beside him, he told me that he could not sleep because of it, and he felt that if he didn't speak, God would never forgive him. That's how it was he came to tell me that you, Israel Zuker, were his father."

"I see—I see! Now I understand!"

Zuker strode across and across the chamber, as though uncertain how to act. At length he disappeared into one of the recesses of the cave, evidently used as a storehouse, and almost as instantly appeared again with a coil of rope in his hands.

"For all you did for my son, I spare your life; but I must keep you here for a few hours. My safety depends on it."

Paul knew that it was useless to protest. He knew well enough that Zuker had the power of shooting him as a dog, and he was not the man to stand any nonsense. So he allowed himself to be bound; and when he had bound him, Zuker brought out some cushions from the recess, and placed Paul on them.

"There! I am making you as comfortable as circumstances will permit," he said. "Gute nacht—good-night. Remember Israel Zuker again in your prayers. Ach! it was good of you to be kind to my boy when others so mocked and hated him. Adieu!"

With these words, he passed swiftly out by the way he had come. Paul rested for a few minutes, thinking quietly over the strange interview through which he had just passed. It was kind of Zuker to spare his life, but he did not much appreciate the prospect of lying there, bound hand and foot, for several hours—nay, it might so happen that Zuker would never return.

His last words had an odd sound. It was difficult to know what he meant by them. He might have an intention of returning, or he might not. Perhaps he was uncertain himself. He knew well enough that he might be arrested at any moment, just as his confederate had been. In that case he (Paul) might lie there, bound hand and foot, for days and nights, gradually getting weaker and weaker, and finally dying of starvation. The prospect was not a very agreeable one.

So Paul determined to do his best to free himself of the coils that bound him. He was a strong boy, and struggled might and main to loosen them; but Zuker seemed to have tied them with devilish cunning. Struggle as Paul would, he was unable to loosen them. And the more he struggled, the more the rope cut into his flesh.

"My! The tightest knots I've ever struck," said Paul, as he lay back gasping.

"Paul!"

What was that? An echo, or some one calling him by name?

"Paul!"

There it was again. Surely it was some one calling him. He tried to turn his quivering limbs in the direction whence the voice came. Was he awake or was he dreaming?

The figure of a boy was creeping towards him—creeping, as it seemed to him, from the shadows in the tunnel. Who—who was it? Was it really a being of flesh and blood? At first it seemed to him that it must be the wraith of the little fellow about whom he had been speaking—Hibbert—but even as the thought filtered through his mind the boy was kneeling beside him, looking anxiously into his face.

It was Moncrief minor.

"Harry!" cried Paul in amazement.

"Are you all right?" came in a whisper from the boy.

"The boy was kneeling beside him,—it was Moncrief minor.... 'Are you all right?' came in a whisper from the boy."

"Right enough, but not altogether comfortable. Where in the name of wonder did you spring from?"

"Is there any chance of that man you called Zuker coming back?"

"No; you may be sure of that."

"Then, first, let me get that rope off."

Paul, as may be imagined, was by no means opposed to that proceeding. So Harry drew out his pocket-knife and promptly severed his bonds.

"Ah, that's better," cried Paul, springing to his feet and stretching his limbs. "It's worth while being tied up, so as to feel how nice it is to be free again. Now perhaps you'll tell me how you got here?"

"There's really no fear of that man, Zuker, coming back?"

"No; I'm sure of it."

"Then I'll explain. First of all, I must tell you that I've done a mean thing. You lost a letter when that scrimmage took place between you and Stan in the Common Room. I found it, and seeing that it was from my father, read it; then I was too ashamed to give it back to you, so I kept it. Hearing that there'd been a meeting about you in the Forum, I took the letter to Stan and showed it to him. As I came away from interviewing Stan, I saw you hurrying through the gates. You looked round, and seemed anxious that no one should see you. That made me curious. I'd just been reading my father's letter to you—remember. I'd begun to see there was some mystery which wanted clearing up. Why shouldn't I have a hand in it? I asked myself. So forgive me, Paul, I followed you."

Paul was silent. How could he blame him? Was it not the same spirit of curiosity which had first led him to that place?

"It was fortunately dusk, and I took good care that you shouldn't see me," continued Harry. "Besides, you seemed to be so taken up with your own thoughts that you scarcely looked round once when you had gained the common. It was easy following you after that. I was never so puzzled in my life when I saw you creeping about amongst the bushes, then disappear through the ground.

"I was so close to you then, that I saw the exact place where you had disappeared, so that it did not take me long to find the opening to the tunnel. I must say that I funked following you farther; but my curiosity grew. I was on the verge of a big discovery. If I followed you, I should find out the secret which would explain the mystery about you, and set you right with the school. Believe me, Paul, that was what I longed for, and I don't think that anything short of that would have made me go farther, and so I felt my way along the tunnel until I could just see you stretched at full length beside the curtains at the entrance to this place."

Paul recalled the sounds he had heard as he made his way along the tunnel. His hearing had not deceived him after all.

"I was still more amazed when I saw that, I can tell you. I was struck all of a heap," went on Harry. "What were you up to? What were you doing there? You seemed to be watching for somebody. Who? I was burning. I got more and more curious. All thought of turning back had gone. I must find out what it all meant. So, when you rose to your feet, and stepped cautiously into this chamber, I just as cautiously crept to the place where you had been lying, and watched you moving about. Then I saw the man you called Zuker enter, and all that went on after.

"It was fearful, Paul. I saw you were in a fix, but I could do nothing to help you. Once I tried to cry out. It was when that man used the long foreign word. I did not understand what it meant at first, though you seemed to; but presently, when you began to say 'Our Father,' I knew what it meant. Then it was I tried to cry out, but no word came from my parched throat. I think it must have been God who prevented me from crying out, for had I done so, it might have been worse for both of us.

"A minute later I could see that a great change had come over the man when you began speaking about your father and Hibbert. Then I was knocked all of a heap again when I learned that poor little Hibbert was the man's son, and that you knew it. I think that the time I passed while I was watching and listening behind the curtain was the most awful I have ever been through—yes, worse than the time on the raft, and that's saying a great deal; but there was one good thing about it—I was beginning to see how we had all wronged you at Garside—what a noble fellow you really are, Paul."

"Humbug! Get on."

"There's little more to tell. I didn't so much mind when the man bound you, especially as I saw that he was going to leave you. I waited till he had gone—long enough to make sure that he didn't mean popping in his head again; then I crept from my hiding-place. The rest you know. I hope you're not sorry I followed you?"

Paul began to think that the hand of God was in this, as it had been in so many other things. It must have been Something Higher than mere chance which had prompted Harry to follow him to that place.

"Heaven only knows what might have happened to me, Harry, if you hadn't followed me. But come, we mustn't waste any more time. We don't want to spend the night in this place."

"Not quite, though I would not mind exploring it some other time," exclaimed Harry, gazing round the chamber curiously. "Plunger would give something to strike on a place like this. It's chalks better than desert islands. Where does that other passage-way lead to?"

Paul had more than once put the same question to him self. That place of mystery had often been in his thoughts since the day he had first visited it, and frequently had he asked himself—Where does it lead to on the other side? He had now seen clearly enough that there must be some way out on the other side, for Zuker had gone that way. If he could only find out, the information might be of some service to Harry's father.

"I don't know, Harry; but I'd very much like to find out. Would you mind waiting here for a few minutes? I won't be long."

"What are you going to do?"

"Going to explore—just a little way. The coast's clear."

"Going to explore? Well, then, I do mind waiting here. If you mean exploring, I mean going with you."

"Very well, Harry, we'll explore together."

So the two boys passed together through the passage on the other side of the chamber.