The sudden sharp crack of a gun came across the calm surface of the sea, and the watchers turning from their fire towards the black object in the distance saw a cloud of white smoke drifting away from it.
"Hooray!" shouted Vickers. "She's seen our smoke-pillar! Shove more on, just to let her know we understand. Saved!—this time, anyway."
Half-an-hour later, a spick and span and eminently youthful-looking naval lieutenant raised his cap to the three folk who stood eagerly awaiting his approach at the edge of the surf.
"Miss Greyle? Mr. Vickers? Mr. Copplestone?" he asked as he sprang from his boat and came up. "Right!—we're searching for you—had wireless messages this morning. Where's the pirate, or whatever he is?"
"Somewhere away to the southward," answered Vickers, pointing into the haze. "He was here two hours ago—but he's about as fast as they make 'em, and he's good reason to show a clean pair of heels. However, we've ample grounds for believing him to have gone due south again. Where are you from?"
"Got the message off Dunnett Head, and we'll run you to Thurso," replied the rescuer, motioning them to enter the boat. "Come on—our commander's got some word or other for you. What's all this been?" he went on, gazing at Audrey with youthful assurance as they moved away from the shore. "You don't mean to say you've actually been kidnapped?"
"Kidnapped and marooned," replied Vickers. "And I hope you'll catch our kidnapper—he's got a tremendous amount of property on him which belongs to this lady, and he'll make tracks for the other side of the Atlantic as soon as he gets hold of some more which he's gone to collect."
The lieutenant regarded Audrey with still more interest. "Oh, all right," he said confidently. "He'll not get away. I guess they've wirelessed all over the place—our message was from the Admiralty!"
"That's Sir Cresswell's doing," said Copplestone, turning to Audrey. "Your mother must have wired to him. I wonder what the message is?" he asked, facing the lieutenant. "Do you know?"
"Something about if you're found to tell you to get south as fast as possible," he answered. "And we've worked that out for you. You can get on by train from Thurso to Inverness, and from Inverness, of course, you'll get the southern express. Well put you off at Thurso by two o'clock—just time to give you such lunch as our table affords—bit rough, you know. So you've really been all night on that island?" he went on with unaffected curiosity. "What a lark!"