"It did," Penny maintained staunchly. "I saw it go to the very end of this street. The lights flashed on for an instant. Then the car seemed to vanish. I think it must have gone into that building." She indicated the Hamilton Manufacturing Plant. The officer surveyed it briefly. "Don't kid me!" he snapped. "Only a Houdini ever went through solid walls!" He climbed back into the police car, saying gruffly to the driver: "Get going, Philips. It was a wrong steer. We must have missed that car at the turn." Penny waited until the cruiser disappeared around the corner. Then she crossed the street and stood staring meditatively at the tall walls of the Hamilton Plant. There was no doorway leading into the building. "It's uncanny," she murmured. "Yet I know very well that car went in there some way." The building was entirely dark. There were no windows on the street side. Only a vast expanse of unbroken wall. "It's too dark to see anything tonight," Penny decided after a brief hesitation. "Tomorrow I'll come back and perhaps make a few interesting discoveries!" And with that resolution, she turned and walked rapidly toward home. CHAPTER X The Vanishing Car Penny fully intended to tell her father of her experience, but she retired before he came home. She overslept the next morning. When she descended to the breakfast room at nine o'clock, Mrs. Gallup told her that the detective had been gone for nearly an hour. "Your father wasn't in a very good mood this morning," the housekeeper informed as she served Penny with a steaming hot waffle. "He complained about the coffee. When he does that it's always because something's gone wrong with his work." "You mustn't mind Dad," Penny smiled. "We couldn't get along without you." Mrs. Gallup sniffed. "I do the best I can. The coffee does taste all right, doesn't it?" "It's perfect." "When your father's working on a hard case he always likes it strong as lye," the housekeeper complained. "But I know he was worried about something this morning." "What makes you think so?" "I heard him muttering to himself. Something about the stupidity of the police. It seems they let some crook get away last night after your father had laid careful plans to catch him." "Not Rap Molberg?" "I think that was the name. Mr. Nichols didn't tell me anything, I just heard him talking it over with himself." "It's the only person he will discuss his business with," Penny chuckled. After Mrs. Gallup had gone back into the kitchen she mulled over the information which the housekeeper had given her. It struck her as probable that the car which she had seen vanish down the dead-end street had been driven by Rap Molberg or one of his confederates. "I wish I could have talked with Dad about it before he left the house," she thought.