‘He isn’t,’ said Brinley quickly. ‘He’s busy looking after my mother.’ She smiled at Mrs Carter. ‘He said I could stay. If I was invited, I mean.’

Mrs Carter took another sip of her wine. Dr Carter placed his glass on the table next to his chair, a fatherly twinkle in his eyes.

‘Well, I’ve got no problem with that. What about you, Pamela?’

Mrs Carter smiled thinly. She had a speck of black olive caught in her front tooth. ‘I don’t mind either, as long as you behave yourselves.’

‘We will,’ said Sara and Brinley together.

Dr Carter fished about in his pocket for his wallet and withdrew a ten-pound note. He pressed it into Sara’s hand. ‘Here you go, girls. Treat yourselves to pizza.’

Sara and Brinley could scarcely believe their luck. The scenario had played out exactly as they had planned. They thanked Dr Carter and disappeared upstairs before he had a chance to change his mind.

Sara ordered pizza on the upstairs phone and rubbed her wrist while her sister and Brinley discussed their outfits.

The younger girl understood that this evening – the takeaway and sleepover – would come at a price, although she didn’t yet know what it would be. For all his pasted-on smiles, their father did not appreciate being put on the spot.

As he had given her the money, he had held on to her wrist and twisted his hand, pinching the delicate skin. Sara had known better than to cry out. She should have expected it. A part of her had expected it. Her father frightened her in a way her mother did not. But like most ten-year-olds, she had a short memory. She was young and impulsive and lived in the moment. It was a simple equation. Like her sister, Sara had wanted Brinley to stay over and that had meant facing down her fears, even if it was only for a few hours.

Years later, when she was in the unit, looking back through the thickened glass of memory, she would remember the early part of that night as one of the happiest of her childhood.

Music. The smell of pizza grease and cheap perfume. Watching her older sister change from jeans to a dress, and back again. Laughter and shushing and the air trembling with the thrill of standing on the edge of something important, the road of life unmapped and full of possibility.

‘What do you think?’

Shannon spun in a circle in front of them both. She was wearing black jeans and a vest-top. A choker circled her neck. Brinley had helped with her hair, and the effect was startling. She looked edgy and grown-up. Beautiful.

Sara, in her plain polo neck and tartan skirt, was fascinated by the transformation, by this glorious stranger who looked a bit like her older sister.

‘Repeat the plan back to me,’ said Shannon, smudging black eyeliner beneath her lashes with her finger.