One night I awoke and the cramps in my legs were surpassed by the urgency of my hunger. I could think clearly. There was a voice in my head – I wondered, briefly, if it was God’s voice – telling me to go downstairs.

When Dr Bellavit caught me, I was sitting in the kitchen. Most of the cupboards were locked but I’d found an open jar of coconut oil in the refrigerator. I hadn’t bothered to search for a spoon. I was eating it with my hands, rubbing my wrist raw trying to dig further and further into the semi-solid white wax.

She didn’t say anything. She just watched as I kept eating, twining my tongue around my fingers, helpless as an animal.

Dr Bellavit believed in punishments for breaking the rules.

‘Please understand,’ she said sadly, ‘that I’m not punishing you. I am punishing the toxic things inside you.’

She didn’t tell me how long I’d have to stay outside. In the morning I was sent out without shoes, or a hat or a blanket. All the colours seemed violent. The hissing of the trees and the wash of the tide were outrageously loud. I stayed out of the sun and kept my eyes shut. I was so still that the island’s creatures stopped trying to avoid me. By evening, tiny lizards were darting over my hands.

Almost asleep, I was startled by the wet flop of a toad landing on my face. I sat up. The toad fell to the sand, the grotesque balloon of its throat contracting and expanding.

Eat it, the voice said to me. I knew, distantly, vacantly, that cane toads could kill me, as they had killed the adders. But still I wanted nothing more than to swallow it whole.

I reached for the toad. But there was no muscle behind the effort. The thing groped away through the long grass.

You snake. I’d said that to Tilly, years ago, when I found out what she’d done. I’d called her other things, too, but that name seemed particularly apt. She had waited and chosen her moment. She’d only needed to strike once.

After I was allowed back inside, I was taken straight to Dr Bellavit’s office.

‘I must discuss something serious with you, Thomasina,’ she said. Her eyes were round like scallops, and I could smell meat in her sweat. She took my hand.

‘Yes?’ I said. My voice sounded like it was coming from somewhere else, as though another person were speaking.

‘Matilda told me about her mother,’ Dr Bellavit continued. ‘She says that her mother suffered with her digestion all her life. There was pain, bloating, elimination issues. She was…’ She paused, consulting her notes. ‘… delicate. Matilda tells me that it was only after she conveyed this to you that you started to complain of similar symptoms.’

‘No,’ I said. I shook my head, which made me dizzy.