"Oh, yes," agreed his chum. "And not only him but the Frenchman as well. I didn't believe it possible that Secor could be in with this German, but perhaps he is, and maybe he'll betray his own countrymen. Either one may give the signal, but if they do we'll be ready for them. No more moving pictures for us, boys, until we get to the war front. We've got to be on this other job!"
"But hadn't we better tell Captain Merceau?" asked Charlie.
"Yes, I think so," assented Blake. "We'll tell him what we think, and what we have done."
But they did not get a chance that day, for there was a submarine scare toward evening—a lookout thinking he saw a periscope—and the consequent confusion made it impossible to have a talk with the commander. The boys did not want to report to any subordinate officer, and so concluded to wait until the next day.
"But we'll keep watch to-night on our friend across the corridor," Blake said. "And on Lieutenant Secor as well. His stateroom is next to Labenstein's, and we can tell when either of them goes out after dark—that is, if we keep watch."
"And we'll keep it, all right!" declared Joe "Now that we know something about what to look out for, we'll do it!"
And so, as evening came on and the lights of the ship were darkened and as she sped along in company with her convoy, the three boys prepared to divide the night into watches, that they might be on guard against what they regarded as an attempt at black treachery.
For somewhere under or on that waste of waters they believed a deadly submarine was lurking, awaiting the favorable moment to send a torpedo at the ship.