I didn’t have to do all that, however, because Carolyn had her key. She let us in and we went down the hall to her apartment, which is on the ground floor in the back. I knelt and studied keyholes.

“If you see an eye staring back at you,” Carolyn said, “I don’t want to know about it. What are you looking for?”

“A sign that somebody tampered with the locks. I don’t see any fresh scratches. Have you got a match?”

“I don’t smoke. Neither do you, remember?”

“I wanted better light. My penlight’s home. It doesn’t matter.” I got to my feet. “Let me have your keys.”

I unlocked all the locks, and when we were inside I examined them, especially the Fox lock. While I was doing this, Carolyn walked around calling for Ubi. Her voice got increasingly panicky until the cat appeared in response to the whirr of the electric can opener. “Oh, Ubi,” she said, and scooped him up and plopped herself down in a chair with him. “Poor baby, you miss your buddy, don’t you?”

I went over to the little window and opened it. Cylindrical iron bars an inch thick extended the length of the window, anchored in the brick below and the concrete lintel above. All the window needed was a few similar bars running horizontally and a few squares of color and it could be a Mondrian. I took hold of a couple of bars and tugged them to and fro. They didn’t budge.

Carolyn asked me what the hell I was doing. “Someone could have hacksawed the bars,” I said, “and fitted them back into place afterward.” I tugged on a couple more. They made the Rock of Gibraltar seem like a shaky proposition in comparison. “These aren’t going anyplace,” I said. “They’re illegal, you know. If there’s ever a fire inspection they’ll make you take them out.”

“I know.”

“Because if there’s ever a fire, that’s the only window and you’d never get out it.”