Suddenly I saw a light for a second. It was up in the direction of the ventilator. Then it went away at once. Then was a strong smell of burning oil and a smell of hot metal. Someone in the next room had lit a lamp. I heard something moving quietly, and then everything was quiet again. The small of oil grew stronger. I sat for half an hour. I tried hard to hear anything, but I couldn't. Then suddenly I heard another sound. It was a very gentle sound, like a small kettle. As soon as we heard it, Holmes jumped up from the bed, he lit the light, and hit as hard as he could with his stick at the bell-pull.

"Do you see it, Watson?" he shouted. "Do you see it?"

But I saw nothing. I did hear something. When Holmes lit the light I heard a low, clear whistle. But I couldn't see anything because the light was so unexpected and my eyes were tired. So it was impossible for me to see what my friend was hitting so hard. But I could see that his face was very white and he looked very angry and upset. Then he stopped hitting, and looked up at the ventilator. Suddenly, in the silence of the night I heard the most horrible scream which I have ever heard in my life.