"Walter Simpson!" cried Ned. "That's my friend of the tree!"
"It is?" cried Tom. "Then things begin to fit themselves together. Simpson is a spy, and he was probably trying to communicate with Schwen. But the latter didn't get the information he wanted, or, if he did get it, he wasn't able to pass it on to the man in the tree. Eradicate nipped him just in time."
And, so it seemed, the colored man had done. By accident he had discovered that Schwen had prevailed on one of the workmen in Shop 13 to change passes with him. This enabled the German spy to gain admittance to the secret place, which Tom thought was so well guarded. The man who let Schwen take the pass was in the game, too, it appeared, and he was also placed under arrest. But he was a mere tool in the pay of the others, and had no chance to gain valuable information.
A hasty search of Shop 13 did not reveal anything missing, and it was surmised (for Schwen would not talk) that he had not found time to go about and get all that he was after.
Soon after Schwen's arrest the "Spy Tree," as Tom called it, was cut down.
"Eradicate certainly did better than I ever expected he would," declared Tom. "Well, if all goes well, there won't be so much need for secrecy after a day or so. We're going to give her a test, and then—"
"Give who a test?" asked Ned, with a smile.
"You'll soon see," answered Tom, with an answering grin. "I hereby invite you and Mr. Damon to come over to Shop Thirteen day after to-morrow night and then—Well, you'll see what you'll see."
With this Ned had to be content, and he waited anxiously for the appointed time to come.
"I surely will be glad when Tom is more like himself," he mused, as he left his chum. "And I guess Mary will be, too. I wonder if he's going to ask her to the exhibition?"