She was convinced that had there been a spring in the room itself she must have discovered it, but it never before struck her that it might be at the back of the closet. She felt that she must satisfy herself on this point whatever the risk of discovery. Accordingly at the usual hour she made her way downstairs. She had put the key in the door, and was in the act of turning it when she heard a noise upstairs. She opened the door and stood looking up the stairs. In a moment she saw a light, and directly afterward Miss Penfold appeared at the top holding a candle in her hand. Knowing she was as yet unseen, Mrs. Conway entered the library and closed the door behind her. Then she hurried to the fireplace, touched the two springs, pulled the bookcase open and entered the secret chamber, and closed the bookcase behind her. She had often examined the lock, thinking that the secret spring of the closet might be concealed here. It was a large old-fashioned one, and moved two bolts, one at the top of the door and one at the bottom. These she had already discovered could be easily opened from the inside. She imagined that Miss Penfold was merely going round the house to see that all was secure, and she had, contrary to her practice, taken the key from the door of the library in order that Miss Penfold might enter it if she chose. But the thought now flashed across her that possibly she might intend to open the secret room; and to prevent this she now thrust the barrel of the pistol she carried in between the back of the bolt and the piece of iron against which it shot, so that the action of the springs could not throw it out of its place. Breathlessly she listened. Presently she heard a sharp click in the wall behind her. She had scarcely time to wonder what this meant when she heard a sound in the lock close to her. It was repeated again and again. Then she felt a slight tremor of the door as if somebody was trying to shake it. Her heart almost stood still. Miss Penfold was evidently trying to open the chamber; and, though she knew the lock could not open so long as she held the pistol in the place, she felt her breath coming fast and her heart beating. For five minutes the attempts to open the door continued. Then all was still again.