“Do you know, she tried to get me to swap for her horrid pair? Nasty little things they were. Named for the rivers.”

“Bishop and Selver.”

“Yes.”

“What does that mean? She also had twins? Why would she want to swap them for Robert and Vincent? What happened, Victoria?”

The woman seemed to focus on Harper for a moment, but then she frowned in confusion. “Where are the boys?” She searched the room with her eyes for a moment, then seemed to forget and resumed staring at the wall.

Harper felt she was losing control of the interview. “Mrs Settle, I think you might be able to help me find this person. If you can remember anything else about her, anything at all.”

“I didn’t go out, after that. In case she came back. Not for eight weeks. I read in a book that staying inside would keep them safe.”

“Did she have long hair, or short? What sort of age was she, do you think?”

“Once I found the book, I kept it under the bed always. Instructions, just in case, you see. Just in case she came back and got inside and somehow managed to swap them.”

“What book was this?” Why was she talking about a book?

“It’s a brewery of eggshells, you need, to trick them. That’s what you need. That’s what the book said. Then she’ll know for sure.”

“A brewery of what?” The phrase was meaningless. If she could somehow steer Victoria back to what she was saying about the woman, she felt she had a good chance of getting some useful information. “Was the woman tall, perhaps? Or not? Shorter than average?”

“If you don’t trick them, you see, you’ll never be sure, because they’re very good at pretending. You don’t want to throw the wrong ones away, do you? Got to be sure. Brew the eggshells. That’ll trick them.”

At that moment, Robert appeared in the doorway.

“What are you doing here?”

“I needed to ask a few more questions. I thought she might remember something this time that could be useful.”

“You should have called first. What have you said to her? She’s all worked up. Look at her.”

Victoria was sitting bolt upright, her neck straining. She stared at something in front of her that neither of them could see.

“I stopped her, that nasty woman. I kicked her. I didn’t need no eggshells, not me. She’s not having my babies. She’s not. And I’m not having hers.”

Robert stepped between Harper and his mother. “You’re frightening her. She doesn’t know what she’s saying.”

“I’m sorry,” said Harper, “but I have reason to believe that your mother might know something important.”

“Whether she knows anything or not, you’ll have to come back another time. She’s upset, can’t you see?”