I started to giggle again. It rose up in my throat. The librarian looked over with an annoyed expression and put his finger to his lips. Boo nodded, replaced the book, and we returned to the privacy of the upstairs stacks. After checking to make sure we were basically alone, she continued the conversation.

“You didn’t die here,” Boo said quietly. “So why do you come here?”

“Would you want to stay in Aldshot all the time? At least here I can read. Got nothing else to do. Read everything in here—twice. Well, most of it. Lots of it’s shite.”

“It’s great how you can pick up the books and turn pages,” Boo said.

“It took time,” he said. “But what about you two? You usually don’t come in pairs.”

“You’ve met people like us before?” Boo asked.

“One or two over the years. But they’re always alone, and always a bit mental.”

Not a great endorsement of my kind. And from the way Alistair was looking at me, I could tell that he hadn’t quite put me in the nonmental category yet.

“We’re a bit special,” Boo said. “I’m a police officer.”

“You’re a rozzer?” Alistair laughed properly for the first time.

“Yes, me,” she said. “We’re working on the Ripper case. The Ripper is . . . like you.”

“What do you mean, like me? You mean dead?”

Boo nodded.

“Dead, but nothing like me. We’re not all alike, you know.”

“Course!” Boo said. “Sorry!”

“I’m not into killers,” Alistair replied. “I was a vegetarian. Meat is murder, you know.”

“I’m really sorry.”

Boo reached out and touched his arm. He looked solid enough.

“How are you doing that?” I said. “I saw someone walk through that other woman.”

“Oh,” Boo said. “It depends on the person. Some people are really solid. Some are a bit more like air. Alistair is more solid. Can you pass through things? Doors, or walls?”

“I don’t like to,” he said. “I can. It takes time.”

“The more solid, the longer it takes and the harder it is. The ones who are more like air, they can do that more easily, but they’re not as physically strong. It’s harder for them to move things. But all ghosts are people, and you just respect them, no matter what they’re like, yeah?”

Alistair seemed mollified by this ghosts’ rights speech.

“Rory is needed for the investigation, see?” Boo said. “And she’s just found out what she can do, and it takes some time to adjust to that. She has this assignment to do, and obviously, she can’t do it. So, I was thinking, maybe you could help?”

Alistair didn’t, to my surprise, walk away or simply evaporate in disgust (because, for all I knew, he could do that).

“What is it?” he asked.