“It isn’t an accident at all,” said Jack, literally.

“That’s right,” said Harry.  “That’s what I meant, too.  Now let’s see.  I think that’s all.  Good thing we came up when we did or he’d have cut the tires to ribbons.  And there are a lot of things I’d rather do than ride one of these machines on its rims —­ to say nothing of how long the wheels would last if one tried to go fast at all.”

He tried the engine; it answered beautifully.

“Now is there a telephone in your father’s house, Jack?”

“Sure there is.  Why?” for Jack was plainly puzzled.

“So that I can call you up, of course!  I’m going after Graves.  Later I’ll tell you who he is.  I’m in luck, really.  He took Dick’s machine —­ and mine is a good ten miles an hour faster.  I can race him and beat him but, of course, he couldn’t know which was the fastest.  Dick’s is the best looking.  I suppose that’s why he picked it.”

“But where is Dick?”

“That’s what I’m coming to.  They may have caught him but I hope not.  I don’t think they did, either.  I think he’ll come along here pretty soon.  And, if he does, he’ll have an awful surprise.”

“I’ll stay here and tell him —­”

“You’re a brick, Jack!  It’s just what I was going to ask you to do.  I can’t leave word for him any other way, and I don’t know what he’d think if he came here and found the cycles and all gone.  Then take him home with you, will you?  And I’ll ring you up just as soon as I can.  Good-bye!”

And everything being settled as far as he could foresee it then, Harry went scooting off into the night on his machine.  As he rode, with the wind whipping into his face and eyes, and the incessant roar of the engine in his ears, he knew he was starting what was likely to prove a wild-goose chase.  Even if he caught Graves, he didn’t know what he could do, except that he meant to get back the papers.

More and more, as he rode on, the mystery of Graves’ behavior puzzled him, worried him.  He knew that Graves had been sore and angry when he had not been chosen for the special duty detail.  But that did not seem a sufficient reason for him to have acted as he had.  He remembered, too, the one glimpse of Graves they had caught before, in a place where he did not seem to belong.

And then, making the mystery still deeper, and defying explanation, as it seemed to him, was the question of how Graves had known, first of all, where they were, and of how he had reached the place.

He had no motorcycle of his own or he would not have ridden away on Dick’s machine.  He could not have come by train.  Harry’s head swam with the problem that presented itself.  And then, to make it worse, there was that remark Graves had made.  He had said Harry would find it hard to explain where he had been.  How did he know where they had been?  Why should he think it would be hard for them to explain their actions?