‘There he is! The man himself!’ Sid Khan, MI6’s distinctly unconventional director of International Counter-Terrorism, half rose out of his chair to greet Luke. Generously proportioned and deceptively casual, he was wearing one of his trademark cherry-pink polo shirts, his own private two-fingers-up to the Establishment, even though it paid his monthly salary. For a man tasked with helping to keep Britain safe from the next terrorist attack by ISIS, Al-Qaida or some obscure far-right extremist group, Khan always managed to appear remarkably chilled.

‘Good morning, Director,’ Luke replied, keeping it polite and formal, as he took the empty seat offered. Khan was still standing, beaming down at him even now Luke was seated. Did they know something he didn’t? He glanced quickly round the room, nodding in greeting. There were six people at the table in that briefing room and he recognized only two. Khan and Angela Scott, who flashed him a fleeting smile. Her pale, freckled face was drawn and worried, but the other four seemed tense and expectant. One had close-cropped grey stubble and looked almost old enough to have served in his uncle’s day in the seventies. The others, two women and a man, he guessed were all in their late thirties, like him.

‘Bloody outstanding, Luke,’ Khan was saying. Luke felt his boss was gazing down at him rather like a father whose son has just learned how to ride a bicycle. It made him feel distinctly uncomfortable. ‘You played an absolute blinder up there!’ Khan continued. For one awful moment Luke wondered if this was sarcasm. He had been in the Arctic for less than twenty-four hours, yet in that time two people had been killed on his watch and one was from a friendly intelligence service. The lawyers were going to be all over him for this. Now he could see everyone looking at him, waiting for him to respond.

‘Just doing my bit,’ Luke said modestly, and flashed a smile.

‘Just doing your bit?’ Khan mimicked, looking round the room with a huge grin. ‘I’d say it’s a bit more than that, young man. He’s only bloody GRU! You’ve nailed it for us!’

GRU? Russian military intelligence? Who was he talking about? Luke’s mind was racing to keep up here. ‘I’m sorry,’ he said, ‘who are you referring to? Not Victor Skeet, surely.’

‘No, not Victor Skeet,’ Khan said patiently. ‘I’m talking about Yevgeny Vasiliev. The Russian in the hut. Patient Zero!’

Khan had sat down now, but he was still looking at Luke expectantly with eyebrows raised. Everyone seemed to be waiting for some kind of reaction from him, but Luke was at a loss to know what the connection was here. And then he got it. ‘Those documents in Cyrillic I sent you last night?’