Burgoyne and his companions were on the horns of a dilemma. If they persisted in their attempt to regain their quarters they would almost certainly be detected, while even if they succeeded they would be unable to return to the cliff. Minalto would have to be left to take his chance, and the gaunt evidence of the night's work would be laid bare with the dawn. If they returned to the cliff there was the possibility that they would have to hide all next day, and be faced with the awkward problem of explaining their absence satisfactorily.

They chose the latter course, and upon returning to the scene of the lowering operations they flung themselves flat upon the turf, lest their silhouettes would betray them to the pirates stationed about the camp and concealed in the bushes on the summit of Observation Hill.

There they lay, hardly daring to stir a limb and maintaining absolute silence for the best part of an hour. Then the searchlight, which had been playing continuously upon the island, was suddenly masked. Twenty minutes later Burgoyne cautiously raised his head and looked seaward. A flickering white light informed him that the vessel was steaming rapidly away.

"Hang on here," he whispered to his companions "I'm going to have a look round."

He was back in a quarter of an hour, with the report that he had seen the pirate guard form up and march through the gate of the compound.

"That leaves us with a tolerably free hand," he added. "I was afraid they'd muster all hands and call the roll. No sign of Minalto yet, I suppose?"

"None," replied Withers, who had been holding on to the rope. "He's a bit behind time. I hope nothing's gone wrong."

"So do I," agreed Alwyn fervently.

Slowly the minutes passed. Momentarily doubts grew in the minds of the three watchers. Even Alwyn's faith in Minalto's powers was waning.

"I'll take on now," he remarked, relieving the Second Engineer at the rope.

He had barely resumed his "trick" when the manila rope was almost jerked out of his hand. From the unseen depths below came three decided tugs.

"He's back, lads," whispered Burgoyne joyously. "All together. Man the rope—walk back."

It was no easy task to hoist the ponderous seaman, but at length Jasper Minalto's head and shoulders appeared above the edge of the cliff. With no apparent effort he swung himself up by the projecting beam and gained the summit. Slipping out of the bowline, he shook himself like a Newfoundland dog, for water was dripping from his saturated clothes.

"I've been there sartain sure," he announced coolly, "an' back agen, sir. If you'm your doubts, sir, there's my 'nitials scratched on ter boat's back-board, fair an' legible-like s'long as you looks carefully."

Burgoyne brought his hand down upon the seaman's shoulder.

"Splendid!" he exclaimed. "You must spin your yarn later, after we've packed up and stowed away the gear. There's not much time. But, in any case, Minalto, you've won your place in the boat."

"Thank'ee, sir," replied Jasper gratefully.

Grey dawn was showing over the eastern height of the island when the four men returned to their huts. Burgoyne reported "all well" to Captain Blair, who, declining to hear details, told the Third Officer to turn in.

"You can't work watch and watch for two successive days unless you have a 'caulk'," he added. "It will be another hour and a quarter before the hands are turned out. Make the best of it."

But the Old Man was wrong in his estimate. No attempt was made to summon the crews of the three captured ships to their forced labour. They were piped to breakfast and then allowed to "stand easy", while armed pirates patrolled the inner circle of huts in addition to augmenting the guards in the two block-houses.

"Something's in the wind," declared Captain Blair. "The vessel that used her searchlight last night is evidently beating up for the island."

Soon there was no doubt on the point. From the compound the heights commanding the harbour and eastern approach to the island were plainly visible. Bodies of pirates were being rushed up to the concealed gun emplacements, which they could reach without being seen from seaward. Others were hurrying towards the tunnel, with the idea of manning the machine-guns that swept the entrance to the harbour and the only landing-place.

"The ball's about to commence," said Branscombe. "Wonder who'll open fire first?"

The prisoners listened in breathless suspense for the crash of the opening contest between the warship—or whatever she might be—and the quick-firers comprising the principal defences of the island. At intervals a powerful syren boomed out its raucous wail, demanding in Morse Code whether there were any people on the island.

Presently the sound came from the south'ard and then the west'ard, but no reply was sent from the pirates lying low on the apparently uninhabited island.

An hour later the captives caught sight of the trucks and aerials of a two-masted vessel proceeding on an easterly course at a distance of about two miles north of the island. Then the two mastheads vanished behind the rising ground; but from the fact that the batteries were still manned the Donibristle's people drew what proved to be a correct conclusion that the vessel had once more taken up a position off the eastern face of the secret base.

At noon, the prisoners still standing easy, Captain Blair called a meeting of officers to receive the reports of the investigating party.

It was Jasper Minalto's recital which created the greatest interest. After parting with Mr. Burgoyne on the shore, he said he swam to the reef, landing without difficulty on a flat expanse of coral. Although the reef averaged twenty yards in width and the state of the tide was almost low-water, the breakers swept far across the coral barrier before they expended their strength. Had it been anything near approaching high-water progress along the reef would have been extremely dangerous, if not impracticable.

But in present circumstances Minalto found the reef "fair going". There were several deep and narrow gulleys to be crossed, while there was a strong tidal current setting out of the only possible boat channel—not taking into consideration the ship passage—which was on the extreme south-western part of the reef.

It required a strenuous effort to swim across the narrow gap, but Minalto expressed an opinion that at dead low-water, or thereabouts, there would be little or no current.

Off the south-eastern end of the island he found ............