Sheltered by a great rock and the underbrush about it, Jane, with Fleck and Thomas Dean, peered eagerly out at a dingy, weather-beaten frame structure which neighborhood gossip had told them was the sheltering place of the “Friends of the Air.” In its outward appearance at least, Jane decided, it was disappointingly unmysterious. It looked to her merely like a cheap summer boarding-house that had gone long untenanted. There was a two-story main building, cheaply constructed and almost without ornament, sadly crying for new paint, and the usual outbuildings found about such places in the more remote country districts. Still from Chief Fleck’s manner she was certain that he regarded their achievement in locating the place as of the highest importance. They had run their two automobiles noiselessly up the lane leading from the main road until they were perhaps half a mile distant from the house and then had concealed them in the woods near-by, being careful to obliterate all traces of the wheel tracks where they had left the lane. Making a détour among the trees they had reached their present position not more than three hundred yards away from the buildings. They had carried the rifles with them, and these now were close at hand, hidden under the log on which the three of them were sitting. Carter, with the other men, under Fleck’s orders, had divided themselves into scouting parties and had crept away through the woods to study their surroundings at still closer range while the waning afternoon light permitted. At first glance one might have been inclined to believe the buildings untenanted. There seemed to be no one stirring about the place, and some of the unshuttered windows on the second floor were broken. The only indications of recent occupation were a pile of kegs at the rear of the house and near-by a heap of freshly opened tin cans. Near one of the larger outbuildings, too, was a pile of chips and sawdust. “There does not seem to be any one about,” whispered Jane. “What do you suppose they do here?” “I can’t imagine yet,” said Fleck with an impatient shake of his head. “The fact that this house is important enough for the Hoffs to visit once a week makes it important for us to cautiously and carefully investigate everything about it. It may be a secret wireless plant away off here in the woods where no one would think of looking for it. It might be a bomb factory where their chemists manufacture the bombs and explosives with which they are constantly trying to wreck our munition plants and communication lines. Perhaps it is just a rendezvous where their various agents, the important ones engaged in their damnable work of destruction, come secretly to get their orders from the Hoffs and to receive payment for their hellishness accomplished.” “It’s all so funny, so perfectly absurd,” said Jane with a nervous little laugh. “Absurd,” cried Fleck indignantly, “what do you mean? It’s frightfully serious.”