s station.

"That was camouflage, Jack, pure and unadulterated camouflage," answered
Tom with a laugh. "I had to do something in a hurry to get that fellow's
gaze off us, or he might have made a scene, and we don't want that. But
if I had made a wager with you about the time, I'd have won, for here
we are, right on the dot, which is unusual in these days, I believe."

"You said something, Tom. But what are we going to do about our spy?"

"Well, if you insist that's what he is, I think the best thing would be
to notify some secret service official. There must be plenty of them
around the station. Every passenger, before he leaves the station, has
to have his papers stamped by the military authorities. Then's your
chance to tip them off about this chap."

"I'll do it, Tom. I'm not going to lose any chances of putting German
enemies out of the way."

It was about five o'clock when the train pulled into the Gare de l'Est,
and the passengers, including many soldiers on leave, prepared for the
joys of Paris. Tom and Jack, proceeding as did the others to the place
designated for the official stamping of papers, found a chance to tell
their suspicions to an officer, and to point out the man Jack suspected.

"The matter shall be attended to," said the military official, treating
the information with the utmost respect, and evidently considering it of
more importance than Tom imagined would be attached to it. "We are
greatly indebted to you, not only because you are of our beloved
aviators, but because you also think to do this for France--to protect
her from enemies within as well as from those who are without. France
thanks you, gentlemen!" and the aged officer saluted the two young men
as though he considered them his equals.

"Well, now that's off our minds we can get down to the real business
that brought us to Paris," suggested Tom. "And that's to find my
father--if he's here. After that we can look up Bessie and her mother,
if you like, Jack."

"Of course I'll be glad to do that, Tom, and I should think that you--"

"Oh, of a surety, yes, as a Frenchman would say. I'll be happy also, to
see our friends again, but I know Bessie will consider--"

"Oh, drop it, will you?" begged Jack, for he could see that his chum was
about to start to rally him about the girl.

"Then," went on Tom, "the first thing to do, in my opinion, is to get to
this address in the Rue Lafayette where dad said he would make his
headquarters,