At just that moment, at least according to the time code from the CCTV camera in the foyer, yours truly was flashing his warrant card and getting buzzed into the building. I then head, with my Costa Coffee double macchiato in one hand and a cinnamon swirl in the other, for the central staircase and make my way up toward the same interview room—at this stage I’m one floor down.

Interview rooms used to be just ordinary offices fitted out with a table, a couple of chairs, good soundproofing, and a place to leave the telephone books when you were finished. These days, a modern interview room has two camera positions, a tape recorder, a one-way mirror, and a separate recording suite from which an enterprising senior investigating officer can monitor several interviews at once or have a bit of a nap. Since at West End Central all of this had to be shoehorned into the space designed in the 1930s as a modest open-plan office, it meant the access corridor outside the interview rooms was a bit narrow. The single CCTV camera that covered the corridor began to malfunction about the time I started up the steps and none of the recording equipment in the interview rooms was turned on. This is all to the good for me, because it means that when I came around the corner and found myself face-to-face with the Pale Lady my thirty seconds of stunned indecision were not recorded for posterity.

Apart from her hair, which had been shorn off into a ragged pageboy, she looked exactly like the witness descriptions: white face, big eyes, disturbing mouth. She was dressed in gray joggers, a salmon-pink hoodie, and she didn’t see me at first because she was attempting to shake PC Phillip Purdy off her leg. He was stretched out on the floor with his left arm, broken in two places I learned later, dragging beside him and his right hand locked around the Pale Lady’s surprisingly slender ankle. One of his eyes was beginning to swell shut and there was blood pouring from his nose.

I don’t know if it was shock or the fact that I had a mouthful of cinnamon swirl, or just because I’d already had a day of weird shit and was getting a bit punch-drunk, but I just couldn’t make myself move.

Purdy saw me, though. “Help,” he croaked.

The Pale Lady looked at me and cocked her head to one side.

“Help,” said Purdy again.

I tried to tell him to let go and move away, but it came out muffled in a shower of cinnamon crumbs.

Without taking her eyes off me, the Pale Lady elegantly lifted one hand and then slammed it down on Purdy’s wrist. I heard bones break and Purdy whimpered and let go. She smiled, revealing far too many teeth—I’d faced a smile like that before. I knew what was coming next. She tensed, so did I, then she surged toward me with a terrifying burst of speed, head thrust forward, mouth open, teeth bared. As she sprang at me I threw my coffee in her face. I’d just bought it. It was very hot.