"Two years ago my sister Julia became engaged to be married. My stepfather made no objection. But two weeks before the wedding, a terrible thing happened. Our bedrooms are on the ground floor, next to each other. That evening Julia came into my room and asked whether I had ever heard a whistle in the dead of night. I said that I had not. She told me that for several nights she had heard a low, clear whistle at about three o'clock, and she could not tell where it came from. She said good night and locked her door. She always locked it, because of the cheetah and the baboon. I could not sleep. About three in the morning I heard the wild scream of a frightened woman. I ran into the passage. As I opened my door, I heard a low whistle, and then a metallic sound, as if a heavy bar of metal had fallen. My sister's door was open. She stood there, swaying like a drunken person, her face white with terror."