At first it was indistinct and blurred, but later, it came into focus. It was the oval face of a girl, dark-eyed, her hair in disorder, a look of unspeakable terror on her face. She raised her hand as if to beckon somebody—probably Jack himself, who was directing the picture. That, at least, was Jack’s view. They had hardly time to get accustomed to the presence of the mystery girl when she disappeared, with such rapidity as to suggest that she had been dragged violently back. “What do you make of that?” asked Knebworth. Michael bit his lip thoughtfully. “Looks almost as though friend Penne had a prisoner in his dark tower. Of course, the woman whose scream I heard, and who he said was a servant! But the window puzzles me. There’s no sign of it inside. The stairway leads out of the hall, but in such a position that it is impossible that the girl could have been standing either on the stairs or the landing. Therefore, there must be a fifth wall inside, containing a separate staircase. Does this mean you will have to retake?” Jack shook his head. “No, we can back her out: she’s only on fifty feet of the film; but I thought you’d like to see it.” The lights came on again, and they went back to the director’s office. “I don’t like Penne, for more reasons than one,” said Jack Knebworth. “I like him less since I’ve found that he’s better friends with Mendoza than I thought he was.” “Who is Mendoza—the deposed star?” The other nodded. “Stella Mendoza—not a bad girl and not a good girl,” he said. “I’ve been wondering why Penne always gave us permission to use his grounds for shooting, and now I know. I tell you that that house holds a few secrets!” Michael smiled faintly. “One, at least, of them will be revealed to-night,” he said. “I am going to explore Griff Towers, and I do not intend asking permission of Sir Gregory Penne. And if I can discover what I believe is there to be discovered, Gregory Penne will sleep under lock and key this night!” CHAPTER XIX THE MIDNIGHT VISIT MICHAEL BRIXAN had had sent down to him from town a heavy suit-case, which contained precious little clothing. He was busy with its contents for half an hour, when the boots of the hotel announced the arrival of the motor-cycle that had been hired for him. With a canvas bag strapped to his back, he mounted the machine, and was soon clear of the town, swerving through the twisting lanes of Sussex until he arrived at the Dower House, behind which he concealed his machine.