‘Wait here,’ Colonel Petrov said, in English, before getting out and closing the door behind him. Luke watched him walk off, his greatcoat reaching almost to his ankles, then talk to the man with the carbine. Twice they turned and looked at him as he sat in the back of the car, feeling caged and tense. When Petrov returned he held open the car door for Luke to get out.

‘Okay, you come now,’ he said in English, which made Luke think he understood a lot more of it than he made out. They picked their way through the wet slush, Petrov leading, as the snow fell around them in fat, wet flakes. He turned a corner to see several more GRU men guarding the door to a garage, weapons held in their gloved hands, all eyes watching him. Petrov gestured for him to go in, but for a second Luke hesitated. If this is where I get whacked on the back of the head, he thought, Vauxhall Cross will at least know my location from the GPS tracker in my phone. And that’s a fat lot of use to me right at this moment. But there was no turning back now: he had to see this one through. Luke stepped through the doorway and into the dim interior of the lockup, his eyes adjusting quickly to the gloom. The place smelt awful, damp, musty, decrepit, and there was something else here that he couldn’t quite put his finger on. Was it fear? Despair? This certainly felt like the kind of place where someone could disappear without a trace.

And there, in the middle of the room, was the reason. Stripped to the waist, his beltless trousers half falling off his skinny frame, his arms pinned behind his back and attached to a chain that went up to a pulley on the ceiling. Luke could see that, suspended like that, the prisoner was struggling to stand upright on the tips of his toes, in an effort to avoid the agonizing pressure on his shoulder blades. Luke stood stock-still, shocked at what he was seeing. This was like Afghanistan all over again, going into a police station with his patrol and finding some chained-up prisoner half beaten to death in a back room. Luke knew what it was like to be tortured – he’d experienced it first-hand in Colombia – and the sight of this wretched individual, guilty or not, sent shivers right through his body. And this wasn’t just wrong, this was dangerous – for him, career-wise. The Service had strict rules about this sort of thing nowadays. If you witnessed torture you had to leave the scene. No exceptions.

So why wasn’t he turning on his heel and walking straight out? There were other men in the room, bulky figures moving around in the shadows, and he sensed everyone was waiting to see his reaction. Calmly and without emotion, he addressed Colonel Petrov. ‘Let him down, please.’