"It's--it's a--a sign." "Was Sir Charles murdered by this gang?" "I don't know--I don't know. Oh!" Penn screamed and clutched again at the side of the car. "You do. This false Mrs. Brown belonged to the gang." "I can't say. I daren't tell you. If I say anything I shall die." "You shall die if you don't say what I want you to say," said Dan between his teeth, and again the machine dipped and towered. "I'll tilt you out, I swear, if you don't tell me who murdered Sir Charles." "I don't know, I tell you," cried Penn desperately, "the perfume has to do with a society of people, who--who--but I daren't speak. I should be killed. I have said too much as it is. And if you reveal what I have said, you will be killed also." "I don't care. Is Mrs. Jarsell connected with this gang?" "I don't know Mrs. Jarsell," said Penn sullenly, although his terrified face showed that he was nearly frightened out of his wits. "Do you belong to this----" started Dan, when a sudden action of Penn took him by surprise. In endeavoring to frighten the man he had flown too low, and the aeroplane was only six feet off the ground, preparing to swing skyward again. The secretary, in desperation, flung himself sideways out of the machine, as it curved at the lowest and fell heavily on the herbage of the Heath. Dan could not stop to see if he was safe or hurt, but soared aloft again to a considerable height. Circling widely he came sailing directly over the spot where the secretary had tumbled out in his desperate endeavor to escape. Already the man had picked himself up and was limping off toward the town as quickly as he was able. "Now," said Dan grimly to himself, "he will have me arrested for attempted murder. That's all right," and he chuckled, although not entirely successful in his endeavor to make Penn confess. CHAPTER X ANOTHER MYSTERY In his anxiety to learn the truth Dan was perfectly willing to be arrested on whatever charge Penn might wish to bring against him. After all, publicity was what he chiefly aimed at, and if he gave his reasons for threatening the secretary, he felt confident that the man would find it difficult to clear his character. Certainly Halliday had not intended to take Penn's life, and had not the man been such a coward he would have simply laughed at the idea of being tilted out of the machine. But his nerves, shaken by the possible danger, had given way, and he had said much which he would have preferred to keep locked up in his heart. But that the aeroplane, by dipping so low, had afforded Penn the chance of escape at the risk of a rough fall, he would have spoken at greater length. And yet, after turning the matter over in his own mind, Dan could not be sure of this.