I hadn’t factored that in, that Bette might actually be intent on seeing Mum. I should have – she had written the letter to Mum, after all, not me, even if I was explicitly mentioned.

‘Um, she’s away at the moment,’ I said. ‘High-flying. Not back for a week or maybe more. So . . .’ This was true. All true.

‘Maybe you will call her then, in that case. In a week? You will stay at least a week? Yes? Maybe longer?’

‘Oh, um. Maybe,’ I said. But Bette clearly needed more. ‘Um, probably a week.’

Bette seemed satisfied. She pressed her palms together. ‘Now, pillowcases!’ she said, and turned and ambled out of the room and down the dark hallway in search of more fine comforts for her long-lost granddaughter.

Once Bette had finally arranged the bed to her liking, and shown me where the toilet was – a tiny room by the back door with only a laundry sink and a showerhead over a cheap plastic shower base, and that I hoped wasn’t all the house had by way of a bathroom – she shuffled off to bed again, saying ‘Goodnight dearest girl’ as she went.

I closed the bedroom door behind her as best I could with all the stuff in the way, and sat down on the bed. Awful. This place was awful. It was horrifying, in fact. How could they live like this?

Torn and faded posters covered the walls, various faces peering out from behind junk and cupboards: mostly Madonna, another woman called Sheryl Crow if the jagged writing across it was anything to go by, a small picture of a young George Clooney in a white jacket with a stethoscope slung around his neck.

Under the squalid surface, this was a typical teenage girl’s room. It had belonged to a girl who’d listened to music, who’d had crushes and favourite television programs. It seemed almost unbelievable that that girl was my mother. My teenage mother. My mother at seventeen, the same age I was now.

I retrieved my memento mori from where I had put it out of harm’s way on top of the cupboard. The picture was an art print as well as a medical illustration. Nassim had shown a talent for finding arty things that I actually really liked, and this one was sciencey but also very funky. The skulls were double-printed in two colours, rust-red and teal, just off centre from each other to give the impression of something slightly out of focus, as though if you put on a pair of 3D glasses the skulls might suddenly jump out at you, unified in their grinning three-dimensional horror.

I hugged it to my chest, as if to protect both it and myself from the chaos around us, and then I leaned it against a ragged bunch of newspapers and sat back on the bed.

I began to shiver. The bus driver had been right. It was freezing. And there was no heater that I could see. I couldn’t bear to undress so I kicked off my shoes, pulled on the thick men’s tube socks Grandma had given me over my own thin socks, turned off the main light, and got in under the covers on the squeaky bed. For a while I tried rubbing my arms with my hands and wiggling my feet against each other, but eventually I just gave in to the cold and lay there staring at the ceiling by the dim blue light from my phone.