You know what the worst part of it was? That I had to do it basically sober, because I needed to remember everything. I couldn’t leave it all up to Drunk Louise and go along for the ride. I had a one-and-a-half-strength gin and tonic while I waited for my cab, and I walked up to the door of Blue Underground feeling basically myself.

I almost got turned back right then. The bouncer asked for my ID, and I looked all through my handbag without being able to find it. I came dangerously close to crying. Why had I been IDed tonight, of all nights? It only happened once in a while, when I somehow gave off the effect of being a teenager instead of an adult.

‘I didn’t think to bring it,’ I told him, with a note of desperation. ‘I’m thirty-three.’

The bouncer sighed, and after another, more careful inspection of me, waved me into the club. I gave him a smile and hurried past.

The inside of Blue Underground looked vastly different in reality to every memory I had. A combination of it being only quarter full tonight, and Sober Louise now being the one to see it. The clientele were different, too. Most of them looked like students or postgrads. Lots of them were non-English. And the music was more poppy. Less club.

I didn’t really care about the music or about anyone else who was in there, though. I was looking at the staff, searching for someone I recognised.

It didn’t take me long. A guy of probably twenty, down at the far end of the bar from me, one with curling hair and an eyebrow piercing, turned to give a customer his drink. He’d been there on Friday. I knew he had. I’d spoken to him.

It turns out that it’s surprisingly easy to get served quickly by a particular person when you don’t care what anyone thinks of you. I shoved my way in and got his attention with a smile and a lift of my credit card. He came straight over, overlooking three or four people who’d been there first.

‘Kronenbourg, please,’ I said, choosing something that would keep him standing still in front of me while he poured. As he flipped a glass up and into place under the tap, I added, in a voice that sounded strangled to my ears, ‘And I need some help. I was in here on Friday. Do you remember?’

The guy glanced at me, and then I saw something change in his expression. He looked uncomfortable. Worried.

‘I don’t know …’

‘I was with a loud, blonde American woman,’ I went on, trying to pretend I was confident Drunk Louise instead of myself, ‘with lots of tattoos. And after I left, something terrible happened. The police must have been here asking questions. They were here, weren’t they?’