‘Yes. Before she opened the roof she shouted in that she was holding a knife and that if I tried anything, she’d stab me to death then leave me down here to the rats.’

‘Rats?’ I said, a sick feeling crawling up my throat.

‘Yeah. They mostly leave you alone. They frightened me at first, but I’m used to them now.’

Rats. Sneaky, hairy, dirty rats. Rats with sharp, yellow teeth and evil, blood-red eyes.

I shivered. Thought about the cut on my wrist. The blood was congealed now. Did that mean the rats would not be interested or would they be drawn by the scent of quite fresh blood?

She must have felt my reaction because she said, ‘Don’t worry, Polly. Honestly, you’re a lot bigger and scarier to them than they are to you.’

Something soothing about the way she spoke made me wonder if she had children. I opened my mouth to ask, then stopped. If she did have children, what had happened to them? They might have been left alone in their home with no one to care for them. They could have starved to death by now – or maybe Mother had done something to them too. Bringing up the subject didn’t seem a sensible thing to do. Not yet anyway.

‘Tell me if you don’t want to talk about it, OK,’ she said, ‘but I can’t help wanting to know why you’re down here?’

She asked the question as if she knew why she was down here. Curiosity got the better of me and I blurted, ‘Why are you down here?’

She laughed – this time a bitter, hard sound. ‘Because she’s mad. She’s always been mad.’

‘Always been mad? What do you mean? Have you known her for a long time?’

She didn’t reply.

Icy fingers of dread unfurled across the back of my neck. ‘Your name’s Olivia, isn’t it? You’re her sister. Her twin sister.’

She was the girl in the photographs. The girl on the bed. The girl surrounded by dolls. The girl Mother said was rotten to her core.

The woman inhaled sharply, said, ‘How on earth do you know that?’

I took a deep breath, unable to believe it.

‘Polly? How do you know my name?’ Her voice rushed out of her, urgent and panicky. She let go of my hand and moved closer to me on the bed.

‘It’s a long story,’ I said.

‘Tell me,’ she urged, finding my shoulders in the dark, her fingers a little too tight. ‘Tell me everything.’

Chapter 42