‘The Nazis didn’t just murder Jews,’ Mum explained. ‘Marilla was a twin, and there was a doctor in that camp who did wicked experiments on twins. It’s why Marilla couldn’t ever have children.’

I burned with curiosity to know what experiments, but I was smart enough not to ask.

My mother’s tone when she spoke about Marilla was filled with pity. But where she saw only a victim, I saw a survivor: someone who’d found the will to keep going, to stay alive, no matter how viciously she was brutalised.

A woman as unlike my mother as it was possible to be.

Marilla fascinated me. She’d been the same age as me when she was sent to Auschwitz. How could she have survived in such a place? So many people older and smarter and stronger than she had died. What made her different?

I started to find excuses to go to the Spar shop, volunteering to fetch my father’s cigarettes and beer. Some days when I couldn’t face going straight home from school Marilla let me hang out in the storeroom or help her stack shelves.

‘Why are you nice to me?’ I asked one afternoon.

She put down the heavy boxes of soap powder she’d been stacking. ‘You think I survived the camps because I was stronger than the rest, kochanie?’ she asked: I knew that was Polish for sweetheart. ‘You think I was smarter or luckier than the others? No, Millie, the worst of us survived: the selfish, the violent, the brutal, the cruel. The best all died.’ She rubbed at her tattoo as if the numbers burned, her expression suddenly bitter. ‘I became like them. I let them kill my humanity. I need to atone.’

I didn’t understand what she meant: I was only nine.

One afternoon in late December I was sitting at the dining table doing my homework when my father came home. He’d been at the pub all day: he reeked of beer, and his trousers had a suspicious stain at the crotch.

‘Why’s she still up?’ he demanded, jerking his thumb at me.

‘It’s only five-thirty, John,’ Mum said.

My mother was a beautiful woman. A clever woman. She had tools she could have used to manage my father, since she clearly didn’t have the guts to leave him. Occasionally, after one of their fights, she’d flee with me and my sister to one of those battered women shelters, with their walls in neutral colours and their rubber mattresses and their giant jars of peanut butter. But after a night or two, she’d call him, and there’d be tears and promises of change, and then she’d go back and drag us with her. I hated her for her weakness. Sometimes it felt like she wanted him to hurt her.