“I’m as sure that they’re gone as I am that I am standing here,” was the reply. “I cruised about on my log for quite a radius, and couldn’t discover a sign of them. I found the motor boat’s buoy, though. She had been untied by some one.”

“But the Betsy Jane? Schooners and succotash! The Betsy Jane!” broke in Pudge.

“Gone, too,” Frank’s voice broke, “but I wouldn’t care about either if I only knew what had become of Harry.”

“Come on up to the hut and we’ll have some hot coffee and talk it over,” said Billy, who saw that Frank, besides being almost numb with cold, was half crazy at the mystery of Harry’s fate.

Frank suffered himself to be led up to the hut and the rest of the night was passed in speculation as to the fate of the missing boy. All three of the lads were pretty sure that the two Daniels had had a hand in the night’s work somehow, but they were far from guessing what had actually occurred.

Soon after daylight the wireless began working. Dr. Perkins notified them from Portland that he expected to arrive that afternoon at Motthaven, and wished them to meet him. Frank found some relief for his wrought-up feelings in informing the inventor of what had occurred.

“Will charter fast boat and be there with all speed,” came the reply through the air; “make the best of it till I come. Am confident that everything will come out all right.”

And with this message the “marooned” trio on the island had to be content. The day was passed in making a careful survey of the island to discover, if possible, some trace of the marauders. But none was to be found. The tide had even obliterated any footmarks they might have left in the damp sand. Thoroughly disheartened and miserable, the boys ate a scanty lunch and then sat down to await the arrival of Dr. Perkins.

It was sundown when a fast motor boat appeared to the southward, cleaving the water at a rapid rate. A quarter of an hour later Dr. Perkins was hearing from the boys’ own lips the strange story of their adventures of the past day and night.

CHAPTER VIII.—THE DERELICT DESTROYER.