It was not pitch-dark, but even the possessor of keen eyesight would have had to look closely in order to make certain that a moving object was a human being and not a dog.
Harry's surmise proved to be well founded, for they quickly discovered a suspicious movement close to the large hangar. Yes, the two Hun spies were undoubtedly there, and already busily engaged in doing something that could only mean trouble for the American escadrille.
Closer the pair of watchers crept. They could now hear the men whispering as they worked, and Tom even believed he caught a guttural German word used. This convinced him their theory was founded on fact, and that these were secret enemies in the camp.
Another half minute and he felt Harry nudge him. That meant the other believed the time had arrived for them to make their leap; and when he felt his companion start Tom stirred himself.
Both let out a yell as they sprang forward. Tom more than half expected to hear an explosion, thinking the Huns, on finding themselves caught in the act, would fire their grenades promptly.
Nothing of the kind came about. Instead both men instantly dropped flat and started to roll away with incredible swiftness, as though escape was the first thought in their minds.
