which
they had entered. The car's course could be followed by the strong ray
its one light threw ahead; and the boys were able to tell when it
reached the road again.

As they expected it returned the same way it had come, probably heading
for the headquarters of the Crown Prince.

CHAPTER XX

JACK CLIMBS A WALL

"What luck we're in to be here, Tom!" murmured Jack.

Carl Potzfeldt had again entered the house and closed the door; and the
air service boys could no longer hear the car speeding along the road.
Jack was quivering all over with excitement. The events that had just
come to their attention filled him with a sensation of wonder
approaching awe.

"It certainly is strange how we've stumbled on this nest of spies,"
admitted Tom.

"And the paper he gave the captain--it must have been a message in
cipher that an incoming pigeon brought from back of our lines, eh, Tom?"

"I guess it was, Jack. We could see it was only a small scrap of paper,
thin paper at that; but both of them handled it as if it were pretty
valuable."

Jack was chuckling, such a queer proceeding that Tom could not help
noticing it, and commenting on it.

"What's struck you as funny now?" he asked, puzzled to account for this
sudden freak on the part of his companion.

"I was wondering," explained Jack, "whether that mightn't be the
doctored message we believed our commander meant to send through some
time or other with one of the pigeons we got that day we went hunting."

"That's possible," Tom agreed, also amused at the thought. "But then,
whether it is or not, it means nothing to us, you understand. We are
here, and must decide on our movements. If that was a bogus message, and
will coax the Germans to make an attack at a certain place where a trap
has been laid, that's their lookout."

"Somewhere about here must be the pigeon loft where those homing birds
have been bred," suggested Jack, following up a train of thought.

"Yes, it may be on the flat roof of the chateau, or in the barn at the
rear," Tom admitted. "One thing is certain, they know only this place as
home; and wherever they're set free their first instinct is to strike a
bee-line for here. Some people are so foolish as to fancy homers can be
sent anywhere; but that's silly. It's only home that they're able to
head straight toward, even if hundreds of miles away."

"Oh Tom! how about Bessie?" inquired Jack eagerly.

His chum considered, while he rubbed his