“Remarkably like that of a bat.” He spoke the words quietly, but in that still darkness, with dawn yet a long way off, they possessed the power which belongs to certain chords in music, and to certain lines in poetry. I was chilled unaccountably, and I peopled the empty corridors of Cray’s Folly with I know not what uncanny creatures; nightmare fancies conjured up from memories of haunted manors. Such was my mood, then, when suddenly Paul Harley stood up. My eyes were growing more and more used to the darkness, and from something strained in his attitude I detected the fact that he was listening intently. He placed his cigarette on the table beside the bed and quietly crossed the room. I knew from his silent tread that he wore shoes with rubber soles. Very quietly he turned the handle and opened the door. “What is it, Harley?” I whispered. Dimly I saw him raise his hand. Inch by inch he opened the door. My nerves in a state of tension, I sat there watching him, when without a sound he slipped out of the room and was gone. Thereupon I arose and followed as far as the doorway. Harley was standing immediately outside in the corridor. Seeing me, he stepped back, and: “Don’t move, Knox,” he said, speaking very close to my ear. “There is someone downstairs in the hall. Wait for me here.” With that he moved stealthily off, and I stood there, my heart beating with unusual rapidity, listening--listening for a challenge, a cry, a scuffle--I knew not what to expect. Cavernous and dimly lighted, the corridor stretched away to my left. On the right it branched sharply in the direction of the gallery overlooking the hall. The seconds passed, but no sound rewarded my alert listening--until, very faintly, but echoing in a muffled, church-like fashion around that peculiar building, came a slight, almost sibilant sound, which I took to be the gentle closing of a distant door. Whilst I was still wondering if I had really heard this sound or merely imagined it: “Who goes there?” came sharply in Harley’s voice. I heard a faint click, and knew that he had shone the light of an electric torch down into the hall. I hesitated no longer, but ran along to join him. As I came to the head of the main staircase, however, I saw him crossing the hall below. He was making in the direction of the door which shut off the servants’ quarters. Here he paused, and I saw him trying the handle. Evidently the door was locked, for he turned and swept the white ray all about the place. He tried several other doors, but found them all to be locked, for presently he came upstairs again, smiling grimly when he saw me there awaiting him. “Did you hear it, Knox?” he said. “A sound like the closing of a door?” Paul Harley nodded. “It _was_ the closing of a door,” he replied; “but before that I had distinctly heard a stair creak. Someone crossed the hall then, Knox. Yet, as you perceive for yourself, it affords no hiding-place.” His glance met and challenged mine.