‘I don’t know,’ said Zach. ‘Do you want it on a scale of one to ten?’

‘Who are they?’ asked Lesley.

We saw him open his mouth to say – who’s they? But Lesley slapped her palm on the table. ‘My face itches, Zach,’ she hissed. ‘The sooner you tell us the truth the sooner I can go home and get out of this mask.’

‘Who are they?’ I said.

‘They’re just people,’ said Zach. ‘You need to leave them alone.’

‘It’s too late for that,’ I said. ‘Has been since your friend shut down the Central Line during the Christmas rush. They’re talking a closed platform for up to six months, they’re talking millions of pounds. Do you really think they’re going to be satisfied if I just stroll up and say “we know who did it but we’ve decided to leave them alone”?’

Zach slumped forward and pressed his head against the tabletop and groaned – theatrically.

‘Give us something we can take upstairs,’ said Lesley. ‘Then we can do a deal.’

‘I want assurances,’ said Zach.

‘You can have my word,’ I said.

‘No disrespect, Peter,’ said Zach. ‘But I don’t want a promise from the monkey. I want it from the organ grinder – I want it from the Nightingale.’

‘If they’re special,’ I said, ‘then there’s a chance we can keep it low-key. But if you want me to bring in my governor, then you’re going to have to talk to me first.’

‘Who are they?’ asked Lesley.

They were, as far as Zach understood it, people that had met up with Eugene Beale and Patrick Gallagher when they were working on the railways south of the river.

‘Not when they were digging the sewers?’ I asked.

‘From before that,’ said Zach. ‘They helped dig the tunnel at Wapping.’

Which explained why Beale’s butty gang had such a reputation as excavators.

‘You say they’re not fae,’ I said. ‘But they are different?’

‘Yeah,’ he said.

‘Different how?’ asked Lesley.

‘Look,’ said Zach. ‘There’s basically two types of different, right? There’s born different. Which is like me and the Thames girls and what you call fae but only because you don’t know what the fuck you’re talking about. And there’s choosing to be different, which is like you and the Nightingale.’ He pointed at me and then frowned. ‘Sorry, there’s three basic types, okay? There’s born, those that choose and those that are made different.’ He pointed at Lesley. ‘Like through an accident or something.’

Lesley stared at his finger and he dropped it.

I was just about to ask what he meant by that, when Lesley told Zach to stop getting off the subject.

‘Never mind about me,’ she said. ‘Are these people born different? Is that what you’re saying?’