‘It was her decision to leave.’ He stared hard at me. ‘Are you going to open that?’

‘No.’ I shoved it in my bag but he snatched it out, tore away the envelope’s flap. ‘What is wrong with you? Who are you and what have you done with my boyfriend?’

But he simply displayed the card to me. Mary and Joseph gazing adoringly down at baby Jesus, and the twinkling night sky above. ‘Who’s Martin?’ he said.

I grabbed it from him. Inside, it said, May we all remember those who love us at this special time of year. Martin. I stood. ‘I’m going home.’

‘I asked you who Martin was.’ Each word was through gritted teeth.

I had only known one Martin in my life, and he was Maxine’s boss at MI5. I would strangle her for this if I could. Had she seriously believed this cryptic message was the way to get me to do what she wanted, despite my saying no? But as furious as I was with her, I was even more furious with Zac.

‘A friend,’ I said.

‘What kind of friend?’

‘A friend of my grandmother’s. He’s about ninety. You should trust me. You shouldn’t open my letters.’

‘I didn’t. It was like that when I picked it up. Must have happened in the post.’

‘I’m not an idiot, Zac.’

‘How did Martin know to address a letter to you at the hospital?’

‘He might have visited my grandmother when she was having a lucid moment, or maybe Peggy ran into him and mentioned what I was doing.’ One lie after another. They came easily.

‘Let me take you home.’

‘I can take myself home.’

I rushed into the house ahead of Zac. He had tailed me the whole way, stalking after me on foot as I stomped from the pub to my car, which must have looked absurd, then following close behind as I drove – he had to run a red light to keep up. I slammed the front door without waiting for him. Let him use his own key.

I went straight to the bathroom and struggled to turn the lock. As ever, it stuck and resisted before scraping loudly when it finally moved. I could hear Zac shouting from downstairs, then bounding up, his voice growing closer.

‘Don’t walk away from me, Holly. You know I hate that. It’s cruel. It’s a form of abuse. It’s not the way to treat people.’

‘I’m getting in the shower,’ I said.

‘The fault is always on both sides,’ he said. ‘It isn’t all me.’

‘Yes it is.’ I turned on the water to muffle his voice and began to take off my things, dropping my coat on the floor.

He was banging so hard on the door I jumped with each bash of his fist against the wood.