I remember the first time I ever saw the spires of Oxford. Unlike most people in my year, I hadn’t been before I came down for interview. My school didn’t bother running outreach trips; none of us were expected to go to university at all, let alone here. I got off a coach on the high street on a freezing December evening, my breath streaming into the cold air. There was no one around. I struggled to follow the map I’d drawn myself from Dad’s road atlas, and when I walked down a small alley into Radcliffe Square, there it was: the dome of the Radcliffe Camera, its lights blazing against the cold starry sky. When I reached college a few streets later, it was like something from Narnia or Tolkien, the tiny gate set in the stone walls, the hidden garden with touches of snow round the edges. And it had me then – I started to want what I’d never even known I was allowed to before. I knew, too, that I would likely not get in. Everyone else on interviews was so loud, so confident, and I shrank back as they hit balls on the pool table in the common room. In the centre of them all, her eyelinered gaze taking everything in, was Karen. I would not have dreamed that we’d both get in, and more, that she’d become my best friend.

More than three years later, Martha Rasby would lie dead behind the same walls. And now I was here again, finally, to try and find out why.

‘Ali!’

Victoria had aged, I saw with a shock. I remembered her as a posh, horsey twenty-year-old, but her hair was touched with grey and her eyes disappeared behind severe glasses. She’d put on weight, too, and the vanished years hit me. We were women in our forties now, as Martha should have been, but she was gone.

Victoria Adams, who’d surprised everyone by being quietly excellent at Chemistry, when we’d all thought she only knew how to ride horses and buy clothes, had become Dean of Admissions at our college five years ago. I’d messaged her on Facebook, pretending I was scoping out a college for Cassie, and she’d warmly invited me to visit. It occurred to me that maybe people in my year had had these same entry points. Ways of being ushered in, of making things easier. That was what privilege meant.

I knew that college would have been winding down at this point in the year, some students busy with Finals and the others slacking off ahead of the summer. The place seemed quiet, no one revising on the lawn like we used to. When I knocked on the door of her office – her name, Dr Adams, painted in cursive script – she came to meet me. ‘Oh, you didn’t bring your daughter?’