But then I stop. The bed isn’t where I expect it. It’s at ninety degrees, the wooden headboard against the adjoining wall, a cheerful purple throw spread across the white duvet. The smell is wrong, too: there’s the vaguest hint of something sickly sweet on top of a suspicion of stale cigarette smoke. I find myself putting a hand on the wall for balance. Florence and the Machine floats up from the kitchen, telling me I’ve got the love they need. Before I’ve made a conscious decision, I’m halfway down the stairs heading for the kitchen. Carrie looks up from inspecting the contents of a drawer as I enter. “This place is at least well kitted out for the basics,” she says cheerfully, bumping the drawer closed with her hip. “I made you a cup of tea.”

“Oh. Um, thanks.” I had been planning to grab the keys and go straight back to the locked room, but I take the tea she is holding out to me. The source of the music is a battered analogue radio in the corner; I have an urge to turn it down, but I don’t want to seem dictatorial.

Carrie picks up her own mug, cradling it in her long-fingered hands. All of Carrie is long: long fingers and long limbs. Even as a child, she was always the tallest in her class. She’s thin, but her frame gives a sense of strength. Rangy, is what she is. We’ve never looked like sisters. “So,” she says brightly, “you have a house.”

I chink my mug against her own, which is almost empty. “Go me. I have a house.” Neatly sidestepping first-time buyer status, I have at the age of thirty-four achieved what is, according to the Financial Times, the dream of my generation: I am now a homeowner. I don’t even have a mortgage. “Not one with any value, to be fair, since I’m legally unable to sell it . . .” I have a house I don’t know what to do with.

“Oh, you’ll sort that out,” she says. Then she goes on, in an uncanny echo of my own thoughts, “I was thinking, when were we last living under the same roof? It must have been just before you went to university, right?” A very different Carrie then: one without permanent smudged eyeliner and purple dye at the tips of her shoulder-length dark hair, one without a gaze that inexorably presses, silently demanding answers. The Carrie I last lived with was in love with ponies and Michael Jackson music and any makeup she could sneak from our mother; she was seven, the same age I was when my mother and I left Scotland, the age I was when my father left me.

“Right.” Half a sister and half a house. And I don’t quite know what to do with either.

“Is it strange, being here?”