‘Blyat!’ he swore in Russian as he went down, twisting away from me. French cops got a second chance; Russian gunmen got no mercy. I put the next round through his back, the one that followed it in his ribs, racking the charging handle of the broken M4 to recock it after every shot like an old movie cowboy fanning a six-gun. The light on his dropped rifle fell away from me, illuminating an inverted skull by the foot of the door in a blazing halo. Despite the glare from the torch I could make out only shapes, not details, in the shadows it raked up around the door. The ossuary was entirely filled with gas. If they decided to play rough and lobbed in a hand grenade, the first I’d know about it was when it went off.

I threw myself headlong down the pile of bones, landing hard on the floor three metres in front of the stone arch entrance. The M4’s laser reached through it, probing the shins, boots, thighs, of the men on the other side. There could have been a hundred men in that tunnel; a thousand. So narrow was the doorway that, as long as there were bullets to shoot with, it didn’t matter: they could only fight me one to one. So fought the Spartans at Thermopylae.

I opened up before they could get into position. Bone shattered; muscle tore; ligaments sheered and snapped. I fired until first one and then another of the rounds from the M4 streaked out strontium red. The shooter in the bar had loaded tracer for his last three rounds. It was an old trick, and I wasn’t a fan: as well as telling you when you were about to run out of ammunition, it let the people who you were shooting at know it, too. It also let them know exactly where you were – although that was currently the least of my problems. I pulled the trigger for the last time on the M4 and sent a final crimson-glowing slug into the solid black mass of the nearest fallen man.

In the silence following the shots, the deep, tearing screams of the wounded rang out.

And then orders shouted in Russian: ‘Vyrubite svet!’ – Kill the light!