The two boys had not gone very far before they came to a pause. It was impossible to see more than a few feet in front of them because of the darkness.

"Let's try to get a light," suggested Paul. "We can get one, I think, in the place we've just come from."

They returned to the chamber. Paul entered the recess from which Zuker had brought the rope and the cushions, and found that it was quite a storehouse; one part of it for provisions, tinned meats, fruits, fish; another for wood, tools, weapons, models; a third, for a curiously mixed wardrobe, which Paul guessed served the purpose of disguise. Here he found a lantern and matches, and thus provided with a light, they resumed their way.

The gallery or tunnel along which they now passed was about two hundred feet long. The width, as Paul roughly judged, was about thirteen feet, narrowing to some six or seven feet at the top. It had been cut through the chalk bed, at a depth of about six feet below the sand which covered it. At the end of this gallery were two passages, extending right and left. Passing down the former, they found it blocked by heaps of sand and chalk.

"It's quite certain we can't get out that way, Harry," said Paul; "we'd better try the other."

So, retracing their footsteps once more, they passed along the other passage. It was not so wide as the one they had already traversed, but the way was clear for a hundred yards or so; then the tunnel came abruptly to an end.

Paul regarded the wall in wonder. There was no way through it. Where, then, had Zuker gone? How had he managed to get out? Paul held the lantern up and examined the roof. It was clear to see that he was standing below what had once been the shaft to the tunnel. There were footholes in the sides.

"Ah, there's the way out! Hold the lantern, Harry, while I try to find the open sesame," said Paul.

Harry took the lantern, and Paul quickly made his way by means of the footholes to the top. He could then see that there was a square space which, though similar in appearance to the rest of the gallery, concealed the entrance to the shaft. He pushed it upward. It gave easily. It was a trap-door, leading into a square, ramshackle shed!

Paul made his way through into the shed, and a minute later Harry followed his example. They closed the trap-door, which then formed part of the floor, and completely concealed the opening into the shaft.

"Well, if that doesn't beat all!" exclaimed Harry, as the trap-door fell. "Mr. Zuker and his confederates must have been very tricky. No one would imagine what's beneath this old shed. Hallo! What's that?"

As Harry spoke a lurid gleam of light lit up the semi-darkness of the shed; only for an instant; then it as quickly died out.

"Seems like a fire somewhere," said Paul, as he tried to open the door of the shed; but it would not open. It was locked on the outside.

"We shall have to get through the window, Harry."

There was a small window on the right of the shed, just wide enough to get through.

"All right. Follow my leader, Paul."

Paul soon mounted to the window and climbed through. Harry quickly followed him. As he reached the ground there came another lurid gleam of light; then it died out as quickly as before.

"There it goes again, Paul. What is it?"

Paul was asking himself the same question. What was it? Whence did the light come? It was a dark night—no moon and few stars. But in the distance they could see lights flitting about like will-o'-the-wisps from the mastheads of ships; so they knew they were not far from the Medway.

"Thought so. We're close to the river," said Paul. "Now that we've found out all that we can, we'd better make for Garside."

"Yes. Hallo! there it goes again! Why—why, it's a ship on fire!" exclaimed Harry.

It was now clear enough to see that Harry was right. A ship was on fire. The flames, at first spasmodic, uncertain, had now gained a complete hold of the ship, and were shooting upward, like fiery serpents, into the sky.

All thought of Garside vanished from the boys' minds as they raced towards the river. As they drew nearer, they could see that the unusual spectacle had already attracted a great throng of spectators to the banks.

Little wonder, for as the flames crept upward to the rigging, writhing inward and outward to the arms, it was a grand, if terrible sight. And there was pathos in it, too; for the ship on fire was one of the great wooden ships in the Navy of the past. Its day of action—of fighting—had long since passed. So, moored in midstream, it had been used as a storeship.

The signal-lights "Ship on Fire" flashed along the river, and a picket-boat from a flagship, with other boats, approached as near as they could to the burning ship. Was there anybody on board? It seemed not—so far, at least, as could be seen.

But suddenly a cry of horror went up from the crowd. A man had suddenly made his appearance on the deck. He rushed about like a hunted fox, trying to elude its pursuers; then, finding it impossible, flung himself, with a strange cry that long haunted Paul's ears, into the river.

Paul knew that the man was Zuker. The picket-boat tried to reach him, but could not. The fire had enveloped the sides of the old ship, and shot out tongues of flame from every porthole. For the space of a minute Zuker's figure was seen silhouetted in flame against the darkness. Then the waters closed over him, and he was seen no more.

"That—that was Zuker. I'm sure of it," Paul whispered to Harry, when he could speak.

"I thought it looked like him, too," said Harry, in an awestruck whisper. "What could he be doing on that ship?"

"Up to no good, I'm afraid; but good or ill, his work is ended now."

Zuker had at last come to his death by the element from which Paul's father had saved him so long ago.

"Yes; I don't think he'll trouble anybody again," answered Harry, as he slipped his arm, with a shudder, through Paul's.

The flames from the middle of the ship were now leaping fifty feet into the air. The river manuals played upon it, but made little or no impression. It seemed to hiss back contempt and defiance as the water fell.

The excitement of the spectators grew, for a new and terrible source of danger had revealed itself. The chains by which the old ship was moored were beginning to give way. If that happened, she might drift, a mass of flame, against any one of the warships lying in her path.

"I say, Paul, this business may get father into a mess," Harry whispered.

Paul had forgotten, for the time, Mr. Moncrief's connection with the Government dockyard. Harry's words reminded him. A dread fear took possession of him. Perhaps the fire had all been designed—perhaps it was the work of an incendiary, and that incendiary Mr. Moncrief's enemy—Zuker. So long as the fire was limited to the old wooden ship it would not much matter, but if it once got from its moorings, it was impossible to say where the mischief would end.

"Oh, you needn't worry about your father, Harry," Paul answered, putting on his most cheerful voice and manner. "No one could blame him for a ship catching fire."

"I don't know so much about that. Pater's held responsible for almost everything. It's a great shame, that's what it is."

Paul thought the same, but did not venture to express an opinion. A buzz of excitement from the crowd broke in upon his meditations.

Looking in the direction in which all eyes were turned, he saw that a gunboat was steaming along the river. It was making for the flaming hulk.

"What's it going to do?" cried Harry, clutching Paul's arm excitedly. "It'll be right into the burning ship."

Paul was too intent on watching the man[oe]uvres of the gunboat to answer.

Suddenly, when it had got to within one hundred yards of the burning ship, it stopped and opened fire, just as though it had entered into action. Its target was the old ship—a mass of flame from bow to stern. The first shell, missing its mark, went hissing into the river. Jets of water shot upward into the air and fell in a sparkling cascade.

Boom! A flash of light from the gunboat, a whiff of smoke. This time the shell finds its target. Myriads of sparks are whirled in a mad dance to the heavens, then drop again like golden rain into the river. Shell followed shell. The old warship, engaged in its last great battle, fought grimly on. Like the old Guard, it refused to surrender. Twelve shots had been fired. Raked from bow to stern, it was a pathetic spectacle, like some huge leviathan lying wounded to death on the water, with its undaunted heart throbbing a requiem.

Shell could not vanquish it, so a charge of guncotton was exploded immediately beneath it; then the old warship gave a lurch. There was a flash of light—its last dying effort. After, darkness. The great tongue of flame was engulfed in the waters.

The boys had been so absorbed in the terrible spectacle that they had taken no heed of time. But when the ship had gone down, they found that it was ten o'clock. Garside was a good three miles distant, so that it would be close upon eleven before they reached the school again.

Three or four search-parties had been formed under the masters, and they met one of these as they neared the gates. It had been decided between Paul and Harry that nothing should be said about their adventures in the cave until Paul had had an explanation with Mr. Weevil. There was, of course, no reason why they should not speak of the exciting spectacle they had witnessed on the river.

"It must have been a remarkable sight," admitted Mr. Travers, the head of the search-party, "but I don't think Mr. Weevil is likely to accept it as an excuse for your long absence from the school. Besides, you had no business to take with you a junior boy."

Harry was about to explain that he had followed of his own accord, but a glance from Paul kept him silent. When they reached the school, they found Mr. Weevil awaiting them in the hall. He seemed to know that something unusual had happened.

"Come to my room, Percival," he said.

Percival followed him to his room, just as he had done on that day when Hibbert died.

"Something has happened. What is it?" he demanded, as he closed the door.

There was no need for secrecy longer, so Paul told the master everything—how he had discovered Hibbert's parentage; how he had discovered the cave, and all the events that had happened in the train of these discoveries up to the moment of Zuker's death.

"Zuker dead!" exclaimed the master, when Paul came to this part of his story. "You are sure of it?"

"As certain as I can be of anything, sir."

Mr. Weevil paced up and down the room with his arms behind him. It was very clear to Paul to observe that he was very much agitated.

"Dead! dead!" he kept repeating; then suddenly stopped, and confronting Paul astonished him by abruptly demanding: "And what do you think of me—eh? What do you think of your master—eh? You think him a precious scoundrel—eh? You think that he ought to be with Zuker in the river—eh?"