“Saw a gleam of it when they were getting into the boat.”

“Yes; but it may have been left on the vessel.”

“No; I’m sure I caught a flicker after the boat started.”

“Well, what sort of a light is it if we can’t see it now?”

“Dark lantern.”

“Eh? Great Scott!”

All the boys, with the exception of Merry, gave a start. Why should the men in the boat carry a dark lantern?

Rattleton, Browning, Diamond, all three of them, flung the question at Frank.

“I don’t know,” confessed Merry; “but it is a part of the mystery.”

It added to the keen interest with which the boys awaited the approach of the boat.