‘She’s young,’ the Surgeon said. I didn’t much like his voice. I heard a trembling in it. The rum bottle glinted like a jewel in his left hand.

There were black rocks inside the coach-house that strained towards each other, cold silver rods, liquids belching in jars. That first time, I was afraid and didn’t want to go inside. But they only laughed at me and pushed me in, saying it was not magic but science, more powerful than scattered bones and blood and feathers. Langton said it was a room for experiments.

‘What are experiments?’

‘A way of proving a thing one suspects to be true.’

‘What thing?’

‘Any.’

‘But why prove it if you already believe it?’

The Surgeon coughed. The tremor had jumped from his voice into his hands. The room stretched around us. Two high arched windows shrouded in old webs, a handful of dead flies spilled into one corner, like rice.

I held up one of the rods.

‘Calipers,’ Langton said, taking them from me, like a knife from a babe.

He told me they were doing very important work in there, sponsored by a very important man. ‘George Benham,’ the Surgeon said.

Langton took the bottle from him, gave a bitter-sounding laugh. ‘England’s finest mind has taken an interest in our little colonial experiment.’

I’d never heard him talk like this with any other slave. It made me bold. ‘Your own experiment? To prove what?’

‘That a man’s whole potential is seeded in his skull, and one can prove that by examining it closely enough. Europe tries to take the lead in the development of this knowledge − men like Linnaeus, Buffon . . . men like Benham – but I believe we can make the real advances here, where we’re better placed for once to take the lead on something. We can make our own names. Though we need Benham to attract a publisher.’ He glanced at the Surgeon. ‘Mind you, he needs us, too. He might have the name, but we have the specimens.’

I’d soon learn. It wasn’t only bodies did Langton’s bidding, it was minds. While I stayed at Paradise he measured mine, watched how it bent, sized it as sure as if he’d gripped it with that cold tool he kept in the cupboard.

‘Make a long story short,’ said the Surgeon. ‘You’re going to help us.’

‘A great help,’ Langton said, lifting the bottle to his lips.

‘What must I do?’

There was a short, low laugh from the Surgeon.

I saw things in that coach-house that I can’t stop seeing now. But worse than the things I saw are the things I did.

In the early days, I stirred indigo and goat’s blood into buckets of piss, to make their dyes, sharpened their nibs, pounced on geese for their quill feathers. I kept my head down to begin with, though I soon lost some of my fear. We were by that time forever cooped up together. And I became something worse than fearful. Grateful.