Thank you so much, she echoed the woman’s voice, so easily. Yes, I understand exactly. You’ve been most kind.

The woman wasn’t watching for her husband’s grey eyes and careless smile. She didn’t see.

And the secret one turned, and walked away, and understood mysteries, and power, and layers of knowledge, for the very first time.

She kept the book, though. And the photograph of the three children, a big blue sofa. And the pack of cards, he’d taught her to count. There wasn’t much else.

A few scrappy presents, which she laid out once a year, on an August morning.

She’d monitored them, the three of them. Knew their names, and their schools, and their first jobs, several rungs up from the start of their careers.

She was almost exactly the same age as the second child, a girl, and she wondered about the days and weeks, in between.

She saw one of the daughters at a party, years later. Silver dress flowing to the ground. A girl who saw everyone else as walk-on characters in her life.

She watched the confidence, built on the frailest of foundations, and sheltered only by ignorance.

Sister, such an unfamiliar word.

And Casey thought: I could break you. Because I know you. And it would only take a second.

But she ducked away, so the girl wouldn’t see her, the spectre at the feast. She was the other girl, the mirrored girl, the girl who wasn’t there at all, not really.

She used the twirl of the hair later, of course. Magpied that imperious happiness, for just a few minutes.

And blazed with anger at the brilliant mind that made her a secret.

21

21

Casey walked out of the station, through the clatter of people and noise and Costa coffee. The Burton-Smiths lived just over a mile from the station, but Casey wanted to walk. She had looked up the house already, the particulars five years old. An exceptional location. One of the most desirable private roads. Superbly appointed.

The road was wide. A few smaller houses here and there, but most had been flattened and rebuilt, sprawling as far as the plots would allow, with indoor swimming pools to the rear. Casey shuddered. It was the sort of road she only visited when a husband had battered his wife to death with a piece of gym equipment.

The Burton-Smith house was empty though, behind the shiny black gates. Casey wandered up the street, glancing around. A silver Audi was grumbling as an Ocado van struggled through a three-point turn. Most people drove, round here.

But Emily walked. Casey soon saw her, walking down the street, eyes on the pavement. Her bulky navy coat was buttoned to the neck. She was carrying a big cotton shopping bag, and a bunch of tulips, buds tight shut. She looked tired, worried, fragile as a daisy chain.