"Do you want a man?"
"Three. The strongest men in your district."
"Why, the surgeon is old and weak!"
"Nevertheless, I want three strong men; and for that matter, prudence really advises me to take twenty."
At one o'clock the next morning a cautious, scratching sound might have been heard in the ceiling of the surgeon's operating-room. Shortly afterwards the skylight sash was carefully raised and laid aside. A man peered into the opening. Nothing could be heard.
"That is singular," thought the detective.
He cautiously lowered himself to the floor by a rope, and then stood for some moments listening intently. There was a dead silence. He shot the slide of a dark-lantern, and rapidly swept the room with the light. It was bare, with the exception of a strong iron staple and ring, screwed to the floor in the centre of the room, with a heavy chain attached. The detective then turned his attention to the outer room; it was perfectly bare. He was deeply perplexed. Returning to the inner room, he called softly to the men to descend. While they were thus occupied he re-entered the outer room and examined the door. A glance sufficed. It was kept closed by a spring attachment, and was locked with a strong spring-lock that could be drawn from the inside.
"The bird has just flown," mused the detective. "A singular accident! The discovery and proper use of this thumb-bolt might not have happened once in fifty years, if my theory is correct."
By this time the men were behind him. He noiselessly drew the spring-bolt, opened the door, and looked out into the hall. He heard a peculiar sound. It was as though a gigantic lobster was floundering and scrambling in some distant part of the old house. Accompanying this sound was a loud, whistling breathing, and frequent rasping gasps.