“What I’m saying is,” Stephen continued, “the ability is rare, but it’s nothing to be concerned about.”

“Ghosts?” I said again.

“This is going well,” said Callum, shoving a handful of fries into his mouth. “I wish you’d done it this way with me.”

“Let me explain,” Stephen said, adjusting his chair a little to back up an inch or so. “The ability to do what we can do . . . it’s not understood very well, but we do know a few things. Two elements need to be in place. One, you have to have the underlying ability. Possibly it’s genetic, but it doesn’t appear to run in families. Two, you have to come very close to death during your adolescence. This part is key. No one develops the ability after eighteen or nineteen. You have to—”

“Almost die,” Callum said. “We all almost died. We all had the trait. Now we all have the sight.”

They gave me a few moments to process this information. I got up and went to the window. There wasn’t much of a view. I could see the brown brick of the building a few feet away, and a pigeon roost on top of the opposite roof.

“I can see ghosts because I choked?” I finally said.

“Correct,” Stephen replied. “Basically. Yes.”

“But I’m not supposed to be worried about it?”

“Correct.”

“So . . . if I’m not supposed to be worried about it, why am I sitting here with you? You said you were police. What kind of police? Why did the police come to tell me I could see ghosts? How can you even be police? You’re, like, my age.”

“No age requirements in our line of work,” Callum said. “The younger the better, really.”

“This is where it gets a little more complicated,” Stephen said. “We didn’t come to tell you that you can see ghosts. We happened to be working, and this happened to you today, and Boo thought you needed an explanation.”

“Working on what?” I said. “What are you doing?”

“We’re assisting with the investigation. You’re a witness. It’s standard procedure to watch over a witness.”

Finally, I did the math. I was a witness. I could see ghosts. I had seen someone on the night of a Ripper murder, someone Jazza couldn’t see, even though he was right in front of her. Someone whom no camera could film. Someone who left no DNA. Someone who walked away without a trace . . .

I had the not entirely unpleasant sensation of falling. Falling, falling, falling . . .

The Ripper was a ghost. I had seen the Ripper. The ghost Ripper.

“I think she’s figured it out,” Callum said.

“What the hell do you do?” I asked. “If he’s a . . .”

“Ghost,” Boo said.

“Then what do you do? You can’t stop him. You can’t catch him. He knows I saw him. He knows where I live.”