‘I threw out all of your booze, everyone’s booze. I thought I’d stopped you. And I searched your belongings, forgive me. But I could not find a drop of liquor anywhere, and somehow you started drinking again.’

He was silent a long time.

‘The doctor.’

‘The doctor had a supply? But he barely ever drinks.’

‘Hmm. The preserving fluid.’

‘What?’ I was too shocked to speak.

‘Bearable with a little water, my darling. Stops the craving, stops the shakes, the visions.’

‘How did you get it from him?’

‘I just asked him. I asked him if he had anything for the symptoms. He’s a doctor, after all. This was at first, you understand, when I thought perhaps I could remain sober. He said that he did, but that it was not conventional medicine.’ He laughed grimly. ‘I had the feeling he rather fancied the experiment.’

‘Preserving fluid?’ My face was in my hands. I could not believe what I was hearing.

‘Yes. It is not…I’ve been…quite ill afterwards.’ He grimaced. ‘But you must understand. The alternative is…I could not tolerate the withdrawals. You saw how bad it became.’

My mind was racing. Other directions, places it did not want it to go.

‘When did this start?’

He thought for a moment. ‘When we were anchored off Hummock.’

The night in Gideon’s cabin; that first kiss in the moonlight. He’d dosed my father.

‘Was it every night?’

‘No, some nights I was able to hold on.’

‘Were you drinking it the night they threw us off Preservation and we had to come back to the Moonbird?’

‘Er, yes, I was. Yes, he prepared me a dose that night, I remember.’

That night. The night Louisa rowed the sea chest out to us and the doctor made his first irresistible plea for me to join him in his cabin.

‘And the night we were pursued and we sailed between the two islands?’

He thought again. ‘Yes…yes.’

‘And each time, he came to you with the preservative?’

‘Yes. Early sometimes, later at other times. If he kept me waiting, I would begin to suffer.’ He paused. ‘Some nights I would nearly rip the jar from his hands.’

It was mid-morning now. A burial party was leaving the front of the house, down below us, carrying picks and shovels. Out here in the lonely islands, the divided twins would be separated for eternity, rotting slowly into the earth thirty miles apart.

Smoke curled from the pipe that chimneyed the scullery. Out further, past an expanse of neatly tilled potato fields, the Moonbird sat at anchor on a steely sea, waiting out this madness.

‘Tell me again what he looks like,’ said my father.

‘Who?’

‘The doctor.’

‘Tall, you know that. Strong, very strong for a man of his age. Greying hair. Handsome in a way, I suppose, despite…’