"So it was an island, eh?" said Mr. Ironsides. "What island was it, Sam?"
"Castle Rock Island!" burst out Tom.
"Yes, sir; that was it, for a fact," said old Sam. "I recognized it by the ruined tower, when the light flared up and showed it."
"Then that is the place where Captain Rangler and that outfit make their headquarters!" exclaimed the professor.
"Yes, and I'll bet a doughnut that that is where Jack and Sandy are confined!" burst out Tom, with blazing eyes.
"Mr. Ironsides, we cannot run off and leave them like this!" he continued in an impassioned way.
"I agree with you, Tom. But what are we to do?"
"Hang about till daylight, and then cruise round the island. We may see some signs of them. Judging from what I overheard on the tug, there is a bare chance they may have escaped."
"Tom Dacre, you are a brave lad," said the inventor, for the second time that night; "and, better still, you mix brains with your grit. That's a combination that's hard to beat in man or boy."