The car stopped in front of the house, and a man jumped out. Tom saw that he wore a uniform of some sort, and judged that he might be a captain, at least. There was a second figure on the front seat, also in the dark-green garb of a soldier, but a private possibly.
The two young Americans crouched amidst the dense bushes and listened. So many thrilling things were happening in rapid succession that their pulses beat with unwonted speed.
Before this the sound of the approaching car must have reached the ears of the man they had seen pacing the floor in the spacious room that looked like a library. There were many books in cases and on shelves, while pictures and boars' heads decorated the walls.
Potzfeldt opened the door just as the officer alighted, and there was an exchange of stiff military salutations. Tom discovered that his guess was a true one, for the man of the house addressed the other as "Captain."
It was too bad that they spoke in German as they stood by the open door. Jack for once bitterly regretted the fact that he had never taken up the study of that language when at school, as he might have done easily enough. It would have paid him handsomely just then, he believed.
The two men talked rapidly. Apparently the officer was asking questions, and demanding something, for in another minute Carl Potzfeldt took an object out of a bill book and handed it to the other. As near as the watchers could make out this object was a slip of paper, very small, but handled as though it might be exceedingly precious.
Jack had a sudden recollection of a correspondingly minute slip of paper which he and Tom had found hidden in that little receptacle attached to the leg of the homing pigeon the latter had shot.
More talk followed between the two men. Presently the man turned and hastened inside again. He had left the door standing open, however, with the German officer waiting as if for something he had come after besides the scrap of paper.
Jack knew now that the man in uniform was from the headquarters of the Crown Prince. That accounted for the numerous marks of car tires which Tom had discovered on the drive. This lonely house by the roadside on the way to Metz was a nest of spies. Perhaps Carl Potzfeldt might be the chief, through whom negotiations were conducted and lesser agents sent forth.
Jack had got no further in his deduction when he saw the tall man returning. He carried a bundle that was wrapped in a cloth, and depended from his hand by means of a heavy cord, or some sort of handle.