The implications of that churned in my mind. He wasn’t planning to keep me. He’d kill me, and make it look like an accident, or suicide. I’d be dead and he’d keep Bex in here with her mother and her sister. Bex who’d told her clients she’d be away for a while.

I turned to Nina. ‘What happens if you try to get out? With that thing in your arm?’

She sighed. ‘He has a method for … He says it is for humanely … putting us down.’

This felt like a dream. A nightmare. I could barely take it in. Humanely putting you down?

‘We’re below the pig barn here,’ Nina said. ‘He has a system to feed carbon monoxide into this area.’

‘Carbon monoxide?’

‘It’s a good way to go, he says.’

I looked at her face. ‘My God.’

‘If any of the microchips go through the doorway, out of this underground place, it closes the vents and activates the carbon monoxide.’

‘Fucking hell.’

‘Or he can activate it from the barn above. With a code. He told us so we don’t try to escape.’

I shook my head. ‘Christ, Nina.’

‘I should have realised,’ Bex said. ‘All those years he didn’t want me in Gritton. He couldn’t risk me finding out. But he was also protecting me. He knew if I stayed, he’d end up putting me in here.’ She looked at Nina. ‘I’m so sorry. I hated you for leaving me, and all the time you were in here. If only I hadn’t been so stupid.’

‘But did nobody report you missing, Nina?’ I said.

‘I had no close relatives at home, and my cousins and friends thought I was happy here. Everyone here thought I’d gone back to Ukraine. And called me a bad mother.’

I shook my head in disbelief. ‘You need to tell us everything you know. We have to work out what’s going on in his fucked-up head and find a way to make him let us out of here.’

Nina shrugged. ‘He thinks it’s okay to keep us in here. Like the pigs in the crates. The crates stop them hurting their babies by accident. Same with us, he thinks. He stopped me hurting my babies by taking them to Ukraine. In his brain that was how it worked. Sometimes too much freedom is a bad thing.’

I could hear my own breathing. ‘He thinks keeping his family in here is like keeping pigs in crates?’

She nodded. ‘We have TV. All the books. Good food. Medicine. Nobody gets shouted at for coming from another place. No children are run over by a car.’

‘But …’ I didn’t know what to say.

‘He must know it’s wrong,’ Bex said. ‘But he can’t help himself.’

Nina turned to Bex. ‘I never thought it was you. Never you. Always Kirsty with the blue on her hands.’