“You do it when you’re scared. You’ve always done it.” She put the laptop on my desk, screen up, paused, the waveform sitting there. “Answer the question.”

“Yes,” I said. “That’s you.”

“How old?”

“Five. It’s the night of your birthday party.”

“The scar night.” Her hand went to her hairline, where there is a line about an inch long that she has had since she was five and that she has, I now understand, been carrying a set of theories about since roughly the age of eight.

“Yes.”