"That settled the mystery of the explosion, and the _Mars_ began to pot at her with the vertical guns, though at first it was impossible to tell whether any hits were made. But after a few shots, all doubts were set at rest, for she came tumbling down like a winged partridge. As soon as she struck the water, boats were lowered, and they rowed to the floating wreckage, where they found you and also the body of a man who had evidently been killed by one of the shots. As the heavier parts of the machine had sunk, we could not tell what sort of weapons she carried, or the number of the crew. "After that, I went aboard the _Mars_ and reported to the skipper what you had told me about your suspicions concerning the _Black Diamond_. He was precious ratty at not having been told before, and I got orders to chase the steamer and search her. We overhauled her in less than half an hour. She's now safely anchored near the Hard, and her crew are prisoners." "It's pretty clear that the waterplane was carried aboard the steamer in sections," said Lawless after a pause. "No doubt they were put together after she left the quay. The whole thing was wonderfully engineered, I must say." "But what about you?" asked Trent. "I imagine you must have had a rather exciting time." "Exciting!" ejaculated the Lieutenant grimly, and then proceeded to relate all that had happened to him after he left the _Knat_. "Well," said Trent at the conclusion, "you scored that time, anyway." "I s'pose so," answered the other, with a sigh. "But if it had only been a Zep and I'd brought it down, there'd have been a cool thou.' waiting for me." CHAPTER V THE HOAX A thin grey mist lay upon the waters, giving the impression of a silvery veil of gauze stretched from sea to sky. The evening was calm, with not a breath of wind stirring, and the sea was ruffled by long, undulating furrows that pursued their way across the surface like great ripples, with never a "cat's paw" nor a speck of foam to break the monotony of their green-grey hue. Looking strangely impalpable and ghostlike by reason of the mist, the destroyer _Knat_ slipped swiftly through the water, heaving gently to the ground-swell. Upon the bridge Lieutenant-Commander Lawless stood smoking a pipe, and near him Sub-Lieutenant Trent reclined against the searchlight, likewise absorbing tobacco smoke and ozone. No other vessel was in sight and the only sound to be heard was the soft whirr of the turbines. "This is what I call balmy and peaceful," remarked Lawless, taking the pipe from his mouth and knocking it against the handrail. "One could almost sing 'A Life on the Ocean Wave.'" "Huh!" grunted Trent; "then it would be balmy without being peaceful." As Lawless made no reply, he looked up to see the Lieutenant staring hard through the mist at a vague, shapeless something which might have been a ship, or a cliff, viewed through the murky atmosphere. "Something ahead of us on the starboard bow," he said.