Deciding that quick action was the best way to trace the mysterious call, Tom at once summoned Ned and they visited the local telephone exchange. There the records were gone over, but aside from establishing the fact that the call was put through from the Waterfield central, nothing was established. From just what station the threatening man had spoken, Tom could not find out. That it was a man’s voice he was certain, but whether or not it was one of the four or five who had held him prisoner in the lonely house Tom could not decide. “But there’s something in the fact that the call came from Mr. Damon’s town,” said Ned. “And he overheard men talking about you the time he was eating in the lunch wagon. It begins to look, Tom, as if the headquarters of the gang was in or near Waterfield.” “Yes, it does,” agreed Tom. “I think we’ll take a run over there. I want to see Mr. Damon on business, anyhow. And we can take in that old house where they had me tied up. I want to see if I can get any clews there.” However, a visit to the lonely shack, which Tom located after some difficulty, was without result. It had long been uninhabited, and the owner, when found, said he knew nothing of the men who had been in it. This Tom and Ned could well believe. A search through the premises revealed nothing of any value as a clew. The ropes which Tom had discarded when he made his escape had been taken away, or it might have been possible to trace the place where they had been bought. “I guess Waterfield is our next and best hope,” remarked Ned, as he and Tom came away from the lonely house. “I think so,” agreed the young inventor. “Mr. Damon may have heard something more.” They found the odd man contemplating his new plane, which had been repaired and taken back to his own private hangar. Mr. Damon led his visitors to his private office, and there Tom told the latest happenings. But Mr. Damon was unable to throw any light on this new development, nor was he able to trace the men he had overheard talking in the lunch wagon. He had tried to get the police to locate them, but without avail. “Well, we’ll let that go for the present,” decided Tom. “Now for something else—my latest idea, so to speak. I heard you say, the other day, Mr. Damon, that you had some loose funds you wished you could invest in a paying undertaking.” “That’s right, Tom, so I have, bless my bank-book!” “Well, I’m thinking of forming a company to exploit my airline express. I find that a large part of Father’s funds and mine are tied up in such a way, in our other inventions, that I can’t get enough ready cash in a hurry, and I need considerable to start this new method of travel. I thought perhaps you might be interested.” “I think I may be, Tom,” said Mr. Damon. “Tell me about it.”