The improvement in the school's attitude to Paul did not last long. The Garsiders who had come over to him with a swing, for some reason swung back with the same alacrity. The juniors who had cheered him to the echo in the dormitory now passed him without a word.

Fortunately, Paul's mind was too much occupied just then with other matters to take much notice of this change. First and foremost in his thoughts was Hibbert. Would he pull through? The progress he made was very slow—if, indeed, it could be called progress. One day he seemed stronger, the next found him as weak as before. A curious thing had happened on the afternoon Paul returned to the school after his interview with Wyndham. Mr. Weevil had sent for him to his room. Paul thought that it was to reprimand him for something or other. He was agreeably surprised, therefore, when the master motioned him to a chair, and in a kindly voice, altogether unlike his "school voice," bade him sit down.

"I understand that you've visited Hibbert once or twice," he began, regarding Paul through his half-closed eyes.

"Now it's coming," thought Paul. "He's going to forbid me visiting Hibbert." Then, aloud: "Yes, sir. I hope you've no objection."

"I did object at first to visitors of any kind, because I thought it would do the lad more harm than good. But I think the objection may be withdrawn as far as you're concerned."

Paul could scarcely believe his ears. Had he heard Mr. Weevil aright?

"He seems to look forward eagerly to your visits, more than to the visits of anybody"—a sigh, so slight as to be almost imperceptible, escaped the master's lips. "It would be cruel to debar the poor little fellow from any pleasure we can give him. Therefore, Percival, I hope you will understand that you are quite at liberty to visit him when you feel inclined."

"It is very kind of you, sir, and I am deeply grateful."

"You will be careful, of course, not to make your visits too long, or not to unduly excite him."

"Oh, yes, sir; I'll be careful of that."

Paul rose to go, thinking the interview at an end. As he did so, the master placed a hand upon his shoulder.

"You have been very good to the boy—God will reward you! The fear sometimes oppresses me that he will not get over this illness."

The half closed eyes were blinking in a curious fashion. Indeed, Paul saw what was suspiciously like a tear slowly making its way down the cheek of the master. His emotion was no longer a mystery to Paul. Hibbert's revelation had thrown a light upon it. He now knew that the man whom he had regarded as without emotion—as one wrapped up completely in his equations and scientific formulÆ—had yet a deeply human side. Hibbert was the son of his dead sister, and he loved him—loved him with a love that was a hundred times greater than that which the boy's own father had ever bestowed on him. And Paul learnt a lesson in that brief interview which he never forgot—that lying deep down in the hearts of most men, sometimes overladen by rust, sometimes in the midst of decay, may frequently be found a vein of purest gold.

"Don't say that, sir. He was looking better the last time I saw him. He will pull round as soon as he can get out a bit."

"I hope your words will come true, Percival; but he's so frail. If he were only strong like you—but there, it's useless talking. It must be as God wills." Then his voice changed to its old frigid tone.

"You can go, sir."

Thus abruptly dismissed, Paul went out.

"Weevil's a puzzle," he said to himself. "I'm as far off knowing him as ever I was; but there seems to be some warm blood in him, and that's something. I thought he was all pothooks and hangers at one time; but he can't be as bad as that. That shows you shouldn't go by appearances. He's not half as black as I painted him."

Paul was very pleased that he could now visit Hibbert without restriction, and that same night he visited him, much to the boy's joy, and sat by his bed, as we have seen, till he slept.

Thus it was Paul took little heed of the school's attitude towards him for the next few days. Then an incident happened which was to absorb his attention still more. Thinking of Mr. Weevil, and his recent interview, his mind went naturally back to that evening when, devoured with curiosity, he had followed him to Cranstead Common. The more he thought of it, the more he wondered what could have become of him on that night he had so strangely disappeared from view before his very eyes. The ground had not swallowed him up, for he had returned to school that same night. What, then, was the meaning of it?

Paul had promised himself that he would make an effort to find out; so, as he had heard nothing from Wyndham, he seized the first opportunity that occurred to visit that part of the common where the master had disappeared. He followed the trail which the master had pursued in the direction of the river until he came to the thickly-wooded part where the trees, furze-bushes, brake, and bramble grew in wild profusion.

This was the spot where he had lost sight of him. At first Paul could see nothing but the brambles. Examining the place more minutely, he found the bushes curiously divided in the centre. Feeling beneath them, his hand came in contact with cold iron. It was a ring, attached to a circular piece of wood, rusty and moss-grown, so that in appearance there was little to distinguish it from the undergrowth. He found little difficulty in moving it.

He thought at first that it would prove to be the entrance to a well, similar to the well in the ruins where he had hidden on the night he had fled from Zuker; but to his amazement he discovered that it was no well, but led to a sloping tunnel cut in the sandstone. That then was the place where the master had so suddenly disappeared. For what purpose? And where did it lead? It was impossible to tell without exploring it. Should he make the venture? Should he enter it?

Paul hesitated for a moment, but only for a moment. The next he entered the tunnel, cautiously drawing over the lid which concealed it. The passage in which he found himself sloped downward, and was at first scarcely large enough to allow him to walk upright. Little of light penetrated into it, and he had, therefore, to walk cautiously along, like a blind man, making sure of every step he took.

Presently the path seemed to broaden. Extending his arms to their full extent Paul could just feel the walls on either side. He proceeded still more slowly, straining his ears to catch the sound of footsteps. All was silent. It was the silence of the tomb.

"My stars, what a queer place! I wish I could only strike a light, so as to have a peep at it," thought Paul. "What can Mr. Weevil do down here? It isn't a cheerful place, even for a man who happens to be very much in love with his own society."

He came to a sudden pause. What was the use of exploring the tunnel further? He could see nothing, hear nothing. So where was the use of groping along in the darkness? It was folly, especially when he might be precipitated at any moment into some hidden chasm. But folly though it might be, Paul could not turn back. A mysterious voice within him seemed to be urging him on. If Mr. Weevil had passed along that tunnel in safety, why shouldn't he? It must have an outlet somewhere, and Paul grew more and more curious to find out what that outlet could be.

"I feel very much like an explorer in darkest Africa," he smiled to himself. "Shall I be coming across an unknown lake presently, or a race of pigmies? Hallo! What's that? Light at last."

Light it was but of the faintest. It came with a faint streak into the tunnel. The darkness was only darkness before, but now fantastic shadows seemed to menace Paul at every footstep he took. Feeble though the light was, it was enough to show him that the tunnel had broadened considerably. Stepping warily along, the light grew stronger at every step, until he at length discovered that the path along which he was so cautiously travelling led into a cave lit with oil-lamps.

Then he came to a sudden pause again, and his heart beat wildly against his ribs, as he caught the sound of voices. The cave was not empty. There was some one inside. Who?

As he approached nearer he saw that a curtain was partly drawn over the entrance. Paul knew that a false step might betray him.

To lessen the risk of detection, therefore, he crawled on hands and knees to the curtain, and eagerly peered through the space nearest the wall.

The cave looked quite warm and comfortable. A fire of anthracite, which sent out plenty of heat but no smoke, burnt on a hearth cut out of the sandstone. Two or three lamps suspended from the roof diffused an Oriental glow, while several warm bear-skin rugs were scattered over the ground.

A couple of guns and two or three cutlasses were hanging on the wall; and what was more astonishing to Paul, several maps and designs. The nature of these it was impossible for him to ascertain. He further noticed that in one niche of the wall was a photographic camera. In another were ship models, in the third the models of torpedoes, engines, and machinery of various kind.

Paul had taken all this in at a glance. He had not yet seen the occupants of the cave, but there appeared from what he could hear, to be only two. They were conversing in low tones at the far end, where the lights from the lamps dimly penetrated. After a while the conversation became more animated, and the two moved to a table at the centre.

"I think we've succeeded in quieting suspicion," said the foremost of the two. As he spoke the light from the lamp fell full upon his face.

It was Zuker, the German Jew!

Paul's glance turned from him to the other man. It was Brockman, the burly ruffian who had seized the bridle of Falcon on the night of his flight to Redmead—the ruffian who struck the blow which caused the gallant horse's death.

"We've succeeded in calming suspicion for the time being," Zuker was saying, "and that is a great point in our favour; but still we must move cautiously. A false step, and down would fall all my plans like a house of cards. We've been very near discovery once or twice, the nearest was when that youngster got ahead of us with the packet. You remember?"

"Remember! I'm never likely to forget it," said Brockman. "I could never understand how it was the youngster slipped through my fingers."

"Well, it doesn't matter so much as it has turned out, for those Admiralty men—the Hansons—have gone to sleep again. They think that danger is passed, that Zuker, the man they so fear and dread, is out of England."

He chuckled softly to himself. Paul grew colder. He knew well enough the youngster they were referring to, no one better, for it was himself. It was quite clear that the letter he had sent from the school to Mr. Moncrief had never reached him. A staggering suspicion flashed into his mind. He recalled that he had entrusted the posting of that letter to Hibbert. Could it have been that Hibbert had failed him, or worse, could it have been that Hibbert had deceived him? Was he not the son of Zuker? But the suspicion only dwelt in his mind for one brief moment, and he felt indignant with himself that it had rested there so long.

How could he doubt Hibbert, the one boy at Garside who had so clung to him and who was at that moment lying on a bed of sickness?

"Heaven forgive me!" he said to himself; then he caught the voices of the men as they again spoke, and listened eagerly.