“Yes, I suppose there are traitorous Frenchmen,” said Blake slowly, “but they are mighty few.”

“But this means something!” declared Macaroni.

And Blake, slow as he was sometimes in forming an opinion, could not but agree with him.

In silence the boys watched the two men at their queer conference.  The tilted mirrors—­one in each stateroom—­gave a perfect view of what went on between the Frenchman and the German, as the boys preferred to think Labenstein, but the watchers themselves were not observed.  This they could make sure of, for several times one or the other of the men across the corridor looked up, and full into the mirror on their own wall, but they gave no indication of observing anything out of the ordinary.

The mirrors were fastened in a tilted position to prevent them from swinging as the ship rolled, and as they did not sway there was an unchanged view to be had.

“I wonder what they’re saying,” observed Blake.

They could only guess, however, for though the men talked rapidly and eagerly, as evidenced by their gestures, what they said was not audible.  Though both transoms were open, no sound came from the room opposite where the boys were gathered.  The men spoke too low for that.

“I guess they know it’s dangerous to be found out,” said Joe.

“But we ought to find out what it’s about!” declared Macaroni.

“Yes, I think we ought,” assented Blake.  “This Frenchman has been in our country, going about from camp to camp according to his own story, and he must have picked up a lot of information.”

“And he knows about our pictures, too!”

“Well, I don’t imagine what we have taken, so far, will be of any great value to Germany, assuming that Lieutenant Secor is a spy and has told about them,” Blake said.

“We’ve got to find out something about this, though, haven’t we?” asked Joe.

“I think we ought to try,” agreed his chum.  “Perhaps we should tell Captain Merceau.  He’s a Frenchman, and will know how to deal with Secor.”

“Good idea!” exclaimed Joe.  “If we could only get him down here to see what we’ve seen, it would clinch matters.  I wonder——­”

But Joe ceased talking at a motion from Blake, who silently pointed at the mirror.  In that way they saw the reflection of the men in the other cabin.  They arose from their seats at the table, and the map or whatever papers they had been looking at, were put away quietly in the Frenchman’s pocket.

He and the German, as the boys decided to call Labenstein, spoke in whispers once more, and then shook hands, as if to seal some pact.

Then, as the boys watched, Lieutenant Secor opened the door of the stateroom, which had been locked.  He stepped out into the corridor, and was now lost to view.

The next moment, to the surprise of Blake and his two friends, there came a knock on their own door, and a voice asked: