How dare he speak of Eustace like that. A retort was on my tongue but I bit it back. Bill’s lazy smile told me that he was mocking me, trying to get a rise. I would not fall for it. We still held the paper between us. It was the key to helping the Leopard Lady but, by dealing with Black Bill, would I be betraying Eustace if I took it? I thought of Eustace’s face. He wasn’t handsome like Lucien or pretty like Vincent. With his crooked smile and the unruly black hair that curled past his collar, he’d looked what he was – a ruffian – but I’d loved him regardless. I took the paper but placed it down on the table without opening it.

‘I insist on paying you,’ I said.

I had precious little but Bill wasn’t a man I wanted to be beholden to. Then it struck me. There was something I was willing to trade.

‘I want you to take this for the information.’

I held out Ellen’s vial of opium. It had turned out to be of some use to me after all. Curious, Bill took the blue glass bottle from me and opened it. Using his finger as a stopper, he upended the bottle, righted it and then licked the dab of powder left behind.

‘Where did you come across this, then?’

‘Never you mind.’

He hesitated for a moment.

‘Your choice. You know what sort of place this Odditorium is, do you? It’s more than a bit of dancing.’

The paper was still on the table. I was scared to ask him, but I knew I must.

‘Tell me.’

‘There’s an evening show,’ he started.

I nodded. I’d had a taste of the evening show in Crillick’s library.

‘But it’s the matinee you want to watch for,’ Bill said. ‘Starts about three.’

He gave a small shudder, no longer smiling or mocking. Bill had seen all sorts and the Blackbirds were not known to shy away from violence. The Odditorium had to be bad if it had this effect on him. What was Crillick putting the Leopard Lady through if an afternoon show could make the likes of Black Bill flinch?

‘They’re running experiments,’ he said.

‘You’re sure?’ I asked, but I knew the answer. I’d seen the glass tubes, the acids and the pointed instruments on the trolley. The blood droplets on the floor of the warehouse. The scabs and sores I remembered were only what was visible. God alone knew how many scars she bore now.

‘Are they experimenting on the child too?’