“So how am I supposed to stay sane?” I asked. “Don’t you think I deserve to know what can be done? I’m defenseless. Show me.”

“Do you have any idea how many forms I’ve had to sign saying that I’d never talk about this?”

“So you’d rather stand around here with a clipboard all day? If you don’t show me, I will stand here and stare at you. I will follow you. I will do everything you don’t want me to do. I am giving you no choice.”

The corner of Callum’s mouth twitched slightly. “No choice?” he said.

“You have no idea how reckless I can be.”

He looked around, up and down the street, toward the square. Then he walked away for a few moments and made a call.

“Here’s the agreement,” he said when he walked back to me. “You don’t tell anyone. Not Stephen. Definitely not Boo. No one.”

“This never happened. I wasn’t here.”

“And it stays that way. I got a call from Bethnal Green station earlier. They’re having a problem there. Come on, then.”

We walked to Liverpool Street station. Along the way, I also counted the cameras—thirty-six that I saw, and probably loads more I didn’t. Cameras attached to the corners of buildings, to traffic lights, in deep window wells and perched high on stone ledges, sharing poles with streetlights . . . so many cameras, and not one of them would do the slightest bit of good when it came to the Ripper.

At Liverpool Street, he flashed a badge to get into the station, and I tapped my Oyster card on the reader. By the time I was going through the gate, he was halfway down the escalator, and I had to hurry to keep pace with him.

“What do they think you do, exactly?” I asked when we got on the train.

“I’m officially employed by the London Underground. They think I’m an engineer. That’s what my file says, anyway. It also says I’m twenty-five.”

“Are you?”

“No. I’m twenty.”

“So what do they do when they figure out you can’t . . . engineer?”

“People get my name and number from other station managers, and they only call me when things are . . . not right. I show up, and the problem goes away. A lot of people, in my experience, really don’t want to know the details. If they knew how many of their problems I fix, how many trains I keep on time . . . I’m probably the most important employee they have.”

“And the most humble,” I added.