"You don't think it possible," inquired John, "for a submarine to lie out there in the bay and send a small canvas boat ashore?"
Ewins shook his head.
"You've forgotten our minefield—a submarine could not pass it, sir."
"No, I haven't forgotten that," answered John; "but suppose the Germans know where our mines are?"
"Then they'd know more than we do, sir," answered Ewins. "Nobody in the fort knows that, except the Commander, and perhaps the Colonel."
"The reason I am asking you," went on John, "is that I have discovered something and want to give you an opportunity of coming down on the shore with me."
"To-night, sir?" inquired Ewins.
John nodded.
"I suppose, Ewins, it seems fantastical and impossible to you, but I have a theory that the Germans intend to bring a boat ashore there. In my opinion, they have been there before to-night."
Ewins's eyes opened wide.