That day, the day she killed Lucy, I stood looking in at my five-year-old daughter from her bedroom door and any last remaining hope I’d had – that I’d been wrong about her, that she’d grow out of it, that somewhere inside her was a normal, healthy child – vanished. I marched across the room and took her by the hand. ‘Come with me,’ I said and led her to my bedroom. Her expression, biddable, mildly interested, only made my fury stronger. I dragged her to the bed and she stood beside me, looking down at Lucy’s head on my pillow and I saw – I know I saw – the flicker of enjoyment in her eyes. By the time she’d turned them back to me they were entirely innocent once more. ‘Mummy?’ she said.

‘It was you,’ I said, my voice tight with anger. ‘I know it was you.’ I loved that bird. I had inherited her from an elderly neighbour I’d once been close to, and during those years of childlessness Lucy had become the focus of all my attention; a pretty, defenceless little creature to take care of, who needed me. Hannah knew how much I loved her. She knew.

‘No,’ she answered, and tilted her head to one side as she continued to consider me. ‘No, Mummy. It wasn’t me.’

I left her standing by the bed and ran downstairs to the kitchen. And there was Lucy’s cage, its door swung open, the tiny headless body lying on the floor beside it cold and stiff. I looked around the room, my eyes darting wildly about. How had she done it? What had she used? She had no access to the kitchen knives, of course. Suddenly a thought struck me and I ran back up the stairs to her bedroom. And there it was. The metal ruler from Doug’s toolbox, lying on her table. I’d heard her asking him for it the day before – for something she was making, she’d said. It lay there now, next to her craft things and I stared down at it as nausea rose in me.

I hadn’t heard Hannah follow me from the kitchen until she slipped into the room and stood beside me. ‘Mummy?’ she said.

My heart jumped, ‘What?’

Her eyes fell to my belly. ‘Is it all right?’

The slight lisp, that pretty, melodic voice of hers, so adorable – everybody commented on it. I bit back my revulsion. ‘What?’ I asked. ‘Is what all right?’

She considered me. ‘The baby, Mummy. The little baby in your tummy. Is it all right? Or is it dead too?’