"Where could he have come from?" asked Beverley. "The Zug isn't anywhere in sight."
"Unless she's off the other side of the island," added Villiers. "Even then he must have started from a much nearer base. We'll have to investigate."
"Why did he?" persisted Beverley. "That's what I want to know."
He received his answer in no uncertain way.
A tremendous roar rent the sky, followed by a rush of air and the noise of cascades of water falling into the sea. Over the spot where lay the wreck of the Fusi Yama the usually placid surface of the lagoon was lashed into a wide cauldron of leaping, hissing foam.
"Fritz again—the dirty dog!" exclaimed Harborough, when the reverberations of the detonation had subsided. "It might have been worse if we had been working on the boat."
Where the two boats, joined by a platform, had been, was a patch of discoloured water, on which shattered fragments of timber were bobbing in the strong sunlight. Had the working-party not ceased work to convey the rival divers to the yacht, no one would have escaped the force of the explosion.
"This is not the work of one man," declared Villiers. "Let's get ashore."
The suggestion was promptly acted upon, and on gaining the beach Harborough and his companions were greeted by the spectacle of Dick Beverley and Pete, armed with rifles, driving before them a couple of the Zug's crew, who marched with arms upheld in the good old-fashioned way they were taught in the Great War.
"Pete and I had been after pigs," explained Dick. "We were on our way back when we saw two strange men lying face downwards on the cliff, apparently watching the Titania. Of course, we couldn't do anything then, except watch them, because the land isn't our private property, but when that explosion went off and they began laughing and shaking hands we thought it time to have a say in the matter. We did," he added grimly, "and they came quietly."