I wondered if I could make myself do it. Pull the tube so the carbon monoxide killed me and the pigs instead of the people below. If Tony died, I thought we’d eventually be found, but it would be too late for me. If Tony didn’t die after all, he’d come back and kill me and dispose of my body and keep the others. If I’d breathed in carbon monoxide, he’d have to be really clever. Make it look like my Victorian boiler did me in, perhaps? I doubted he’d get away with it.

I thought Bex was considering what I’d said. If I was going to die, I wanted to take Tony Nightingale down with me. I clutched my knife and remembered another case I’d worked on where a murder victim had managed to communicate that it wasn’t an accident. I’d do the same. I’d carve it on my skin. Under my arm where Tony wouldn’t look. I’d carve a message that told them it was him and made them look in this barn. My body would be the clue that made them find the others. It was almost poetic.

A voice from below: Bex. ‘Don’t you dare save us and kill yourself. We don’t want this life! We’d rather die.’

Was that what they all thought? Or just Bex? Nina and Sofia had already survived thirty years of captivity.

Bex’s voice came louder from below. ‘Can you reach to let any of the pigs out?’

I looked at the pigs in their cages. I was chained to a wall in a dark barn but I still had more freedom than the pigs. I stared into the eyes of the closest. She gazed back. There was a patch on her face. She had an intelligent look. A creature in a tiny cage with such an intelligent eye. There were too many horrors bound up in that thought. ‘Yes,’ I said. ‘I can reach the nearest one. But she can’t escape. The barn door’s closed.’

And then I remembered. The pigs had been taught to fetch. ‘The pigs …’ I said. ‘Could the pigs help us?’

A murmuring from below and then Bex spoke again. ‘What’s within your reach?’

I looked around me. ‘There are some bags of stuff. Pig food, I think. And a couple of coats hanging behind me. And a few empty hessian sacks.’

‘Have you ever trained an animal?’

I looked at the pig, the huge pig, and felt a flush of adrenaline in my stomach. ‘I clicker-trained my cat to do a high five.’ I pictured neat little Hamlet raising his paw. A very different proposition to a pig the size of a small car.

‘Can you hear me clearly? I’m right by the grille.’ Bex’s voice was quieter. Speaking rather than shouting, but I could hear her.

‘Yes,’ I said.