‘Fine,’ Knox said. Then he shifted his weight, pulled his arm back, and slammed his fist into the side of White’s face. White took a couple of stumbling steps backwards before stopping and righting himself. He felt a bubble of blood on the edge of his lower lip.

‘That should do it,’ he said.

‘Sorry,’ Knox replied, moving towards the door. ‘And thank you.’

‘One more thing,’ White said, leaning one hand on the table and caressing his jawbone with the other. ‘I reviewed the calculations you gave me. They’re crude and unsophisticated, but with a little refinement they’d work. If Peterson has them too then Pipistrelle is blown.’

It took Knox less than ten minutes to get out of Leconfield House and run across Mayfair. The whole way he thought about what else Peterson might be handing over to the Russians along with Valera. He didn’t have the papers Knox had discovered, but Knox had no idea what Peterson might have extracted from the Italians before killing them. Or what he might have taken from MI5. If he’d somehow managed to pass on information about Atlas, it would be an even bigger disaster than London being covered in undetectable listening devices, stealing all the West’s secrets. With a supercomputer, Russian intelligence capabilities would take a massive, and terrifying, leap forward. No one and nowhere would be safe.

Knox slowed to a walk in Conduit Street, ignoring the burning of his scar and the dull ache that still covered his side. He found Bennett sitting in White’s Anglia, staring so intently at the turn-in to the Richmond that he had to bang on the passenger-side window to get her attention.

‘How was your night?’ she asked, unlocking the door to let him in.

‘Uncomfortable,’ Knox replied.

‘Ditto.’

Knox told Bennett that the man she’d seen with Valera was Nicholas Peterson, Manning’s deputy.

‘So Manning is still behind all this?’

‘I don’t think so,’ Knox said. ‘I think he’s a patsy. Peterson is the mole and he used Manning to deflect attention as he burrowed deeper into MI5.’

She filled him in on the details of the morning that White hadn’t had time to pass on, and told him that she hadn’t seen Peterson or Valera leave the hotel, or the black Jaguar come back.

‘Unless they slipped out when I was on the phone to White, they’re still in there.’

‘So we just need to walk in and ask which room the MI5 traitor and kidnapped Russian defector are staying in,’ Knox said.

‘We only need to get past the front desk,’ she replied. ‘And I’ve got a plan for that.’ She pointed at a small newspaper kiosk down New Bond Street that had a rack of London maps hanging off its awning. ‘We’re just a couple of tourists coming back from our morning stroll.’