The underground ghost stations were part of Parisian urban legend. Ben knew about Saint-Martin, though he’d never been inside.

‘It was taken out of service eighty years ago, at the start of the war,’ he explained for Roth’s benefit. ‘The Salvation Army use it as a homeless shelter. It’s even got a street entrance on Boulevard Saint-Martin that the public can just walk into. I can’t believe anyone would think of making it their hideout, let alone to store a hostage in.’

Jafari shook his head. ‘There’s another way in. It takes you to parts of the system where nobody ever goes. They’ve been closed up so long, hardly anyone knows they even exist.’

‘You’ve been down there?’

‘Once. A couple of times.’

‘You know where they’re keeping her? Have you seen her?’

Jafari nodded reluctantly. ‘I was with them when they took her there.’

‘Piece of shit,’ Roth muttered, shaking his head in disgust.

‘Listen to me, Hasan,’ Ben said. ‘There’s only one way you get out of this. That’s by taking us to the ghost Métro station. Tonight. Now. You do that, I promise we won’t hurt you.’

Jafari stared at him, as though he was thinking hard and working out his options. ‘I’ll get you inside,’ he agreed after a beat. ‘Whatever you say.’

Roth was looking deeply unhappy. Ben took him aside and asked quietly, switching back from Arabic to English, ‘Do we have a problem?’

‘Damn right we have a problem. This asshole is more than happy to show us the way. Because he’s setting us up to walk into a trap. How many of your hardcore jihadis do you suppose are guarding her down there, packing Kalashnikovs and Uzis, or sitting waiting for us with their thumb on a goddamn detonator switch? Five? Ten? And two guys are gonna go waltzing in there alone, deep into enemy territory with no backup and nothing more than a couple of pistols? Forget it.’

‘I agree, it’s an uncertain proposition. But it’s the only way we can get to Segal’s wife.’

‘So what? I mean, I feel for the lady, but you can’t always save them all. Why take the risk?’

‘Because she’s the best chance we have of bringing Segal in,’ Ben said. ‘Once she’s free, Nazim has a lot less hold over him. He might be willing to jump ship.’

‘Hm. Long shot.’

‘And because I’m not leaving an innocent woman down there with a bunch of trigger-happy maniacs,’ Ben said. ‘That’s just how it has to be.’

‘What are you, the white knight?’

‘If you’re not up for it, fine. You stay behind and I’ll go alone. It won’t be my first time.’