The island was never quiet. It wasn’t just the swishing of palms, the woody scrape of their tips against the windows of the house. It was birds screeching in the mornings, frogs bleating in the evenings. And all through the days and nights the electric buzz of insects was in the air and the grass. They would cease when you stepped near, begin again when you were far enough away.

One evening, about two weeks after we’d arrived, Tilly said, ‘I was allowed rice today.’

We were sitting on the beach and the wind was blowing. The sand stung our bare limbs.

‘Rice?’ Even the word was delicious. I thought of the hot grains, the starch they would leak, of chewing them into a gluey mess.

‘Because of my progress,’ Tilly said. ‘You’re still on water?’

‘Water, coconut oil, sometimes an apple. And coconut paste.’

‘I hate that paste.’

‘I can’t believe she gave you rice.’

‘My toxicity is lessening. She thinks I can handle it.’

My gut clamped. Tilly covered her feet with sand.

‘Sorry,’ she said. ‘I shouldn’t have told you.’

But I could tell how pleased she was. I could hear it in her voice. Like when she passed a piano exam I hadn’t taken, or was accepted into the accelerated English class at school.

Gordon hadn’t believed we were sisters. Not at first. ‘She looks nothing like you,’ he’d said. It was the first night I’d brought him home and we were lying in bed, facing one another in the darkness. Tilly was only inches away, on the other side of the wall. But in the dark, that wall was invisible.

In the beginning, when Dr Bellavit explained the entire process to us, she said, ‘I’m telling you this now, before the toxins within you feel threatened and begin to react. These toxins are like any enemy. As you wear them down, they become more desperate, more violent; you must have the fortitude of spirit to see them out. Do you understand?’

I thought of this as the weeks passed at Harbour. Dr Bellavit was giving me extra cleanses, extra massages; some days there would be a small, dry square of bony white fish, but on others I was back to only coconut water.

We had been warned that the ‘final stage’ would affect each of us differently. Some people were unable to sleep. Others had terrible spasms. Some entered a state of euphoria; sadly, I wasn’t one of them. For me, it was my legs. They began to fail. They would shudder as I walked; I couldn’t go downstairs without leaning on the banister, the muscles in my arms and chest quivering.