When he was fully assured of this, he crept into the room and with his fingers explored every inch of the floor. The apartment was so small that this was not much of a task, and before long his hand came in contact with a match. It had been lighted and the softness of the charred end told him that this had been done recently.
This then was the "firefly"!
He continued his search with renewed caution and soon found a cartridge. He knew from the feel of it that it was of the kind used in the rifles with which the American troops were equipped. It was still warm, as though it had been recently in a belt close to a man's body.
But what was a man doing in that lonely spot at that hour of the night?
Was he a prowling spy from the German camp who had made a daring incursion into the American lines?
He must solve the mystery. With every faculty at its highest pitch, he moved out into the open.
A slight rustling in the forest near by fell on his ears. It might have been made by some woodland creature, but to his strained senses every sound, however slight, suggested a possible clue.
He listened intently and heard it again, but this time it was a trifle louder than before.
He rose to his feet and with catlike tread moved in the direction of the sound. As he drew hearer he heard it more plainly. And now his patience was rewarded, for he distinctly heard the low tone of a human voice.
And if it was a human voice it must of necessity be an enemy voice, for no friend of his or of Uncle Sam's could be in that place at that hour on a legitimate errand.