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? "There isn’t any answer," he said to himself. "And, if there was, I’m a juggins to be trying to find it now. I’d better keep my mind on this old machine, or it will ditch me! I know what I’ve got to do, anyhow, even if I don’t know why." Mile after mile he rode, getting the very best speed he could out of the machine. Somewhere ahead of him, he was sure, riding back toward London, was Graves. In this wild pursuit he was taking chances, of course. Graves might have turned off the road almost anywhere. But if he had done that, there was nothing to be done about it; that much was certain. He could only keep on with the pursuit, hoping that his quarry was following the straight road toward London. And, to be sure, there was every reason for him to hope just that. By this time it was very late. No one was abroad; the countryside was asleep. Once or twice he did find someone in the streets of a village as he swept through; then he stopped, and asked if a man on another motorcycle had passed ahead of him. Two or three times the yokel he questioned didn’t know; twice, however, he did get a definite assurance that Graves was ahead of him. Somehow he never thought of the outrageously illegal speed he was making. He knew the importance of his errand, and that, moreover, he was a menace to nothing but the sleep of those he disturbed. No one was abroad to get in his way, and he forgot utterly that there might be need for caution, until, as he went through a fair sized town, he suddenly saw three policemen, two of whom were also mounted on motorcycles, waiting for him. They waved their arms, crying out to him to stop, and, seeing that he was trapped, he did stop. "Let me by," he cried, angrily. "I’m on government service!" "Another of them?" One of the policemen looked doubtfully at the rest. "Too many of you telling that tale to-night. And the last one said there was a scorcher behind him. Have you got any papers? He had them!" Harry groaned! So Graves had managed to strike at him, even when he was miles away. Evidently he, too, had been held up; evidently, also, he had used Harry’s credentials to get out of the scrape speeding had put him in. "No, I haven’t any credentials," he said, angrily. "But you can see my uniform, can’t you? I’m a Boy Scout, and we’re all under government orders now, like soldiers or sailors."