"That is my opinion," said Jack.
"Good; then I'll pass the word along. Good-bye."
Davis moved toward the window and a moment later disappeared on the outside.
"Now," said Frank to Jack, "just what did you tell that fellow? I couldn't hear all that whispering."
"Well," replied Jack, "I told him we had learned very little; but that the secret of the whole affair was at the mouth of the Thames; that that was where we were heading for when we were captured."
"And did you give him some kind of a hint as to the nature of the mystery?"
Jack smiled.
"Well, yes," he said. "I told him he would find some queer explosives there and a large number of swift torpedo boat destroyers, equipped with submarine nets. I told him that these made nightly raids into the Channel and the North Sea and thus disposed of the German submarines."
"And he believed it?"
"He seemed to. But that was the best I could do on short notice and knowing no more than I do of the matter."