Watch the door.

Ice cracked in the silence as the mass of the building shifted by a degree, moved by its tectonic forces. Over the minutes, echoes came sharply from the walls of the buildings around it as the guests began leaving the party and getting into their cars and slamming the doors.

Certainties, then, consider the certainties. Vishinsky would never give up, would have me found and seized, and then would have me shot. This was certain. I couldn't stay here on the roof forever, even if no one came to search it. This too was certain. But if I could make that leap across the gap between the buildings without going down, without killing myself, I could use the drainpipe on the wall of the next building, and perhaps get to the ground, get to the ground and away. This at least was not certain, nor was death in the attempt.

Therefore make the attempt.

Voices from below, voices and laughter as one by one the revellers took their leave, the steam from their breath laced generously with vodka. Light flooded the walls of the buildings as the pinions bit into the starter-bands and the cars moved off with their chains clinking across the snow, leaving me in the gathering silence with a sense of departure crucially more personal, and before too long: we have presentiments, my good friend, do we not, when we feel the party may be over now, and have no wish to go.

I crossed the roof towards the parapet, my shoes crackling on the snow as Ipassed close to the staircase door in the instantwhen it was pushed open and the guard looked out at me and swung up his gun.

He smelled of sweat, athlete's foot, and chewing-gum.

I would have liked to know his name. That's always important when death has to be dealt.

We were lying side by side on the brittle snow; his legs were drawn up. He was trying to find some kind of purchase for his splendid new Nikes, some way of kicking out and giving himself leverage. His breath rose in small clouds, and mine with it, as if we were brothers, which of course we were: all men are brothers.

When I'd moved in on him a minute ago, chopping down with a heel-palm against the muzzle of the AK-47, his finger hadn't had time to thrust itself into the trigger-guard; the gun had not fired. It was lodged between us.

The door of the staircase was still open. Even if I could have moved, I wouldn't have closed it. If there were any more footsteps on the concrete stairs I wanted to hear them. I couldn't move because we were in a double check, the fancy name for this situation, dreamed up by some chess-playing bloody poet in the Bureau. But I suppose -

Watch it.

He'd made an attempt at moving, this man, my brother, at first relaxing by infinite degrees so that I wouldn't notice, then blasting the motor nerves with signals; but I had noticed, and he didn't get his half-fist any farther than an inch or two, aimed at my throat. He'd been trained in close combat, which was not good news; on the other hand it made him more predictable, since I would know most, perhaps all, of his moves.

Sweat running on both of us: the muscular tension was enormous because neither wanted to let go, to get ourselves, in other words, killed. To extend the fanciful idiom, that would be checkmate.

Earlier, thirty or forty seconds ago, he'd tried to reach the trigger of the assault rifle, in the hope of releasing a burst as a signal to the other guards. There was no chance at this stage of turning the muzzle on me – I've told you, these things are totally useless at close quarters.

I could feel his heart-beat. He could feel mine. They wouldn't slow for a long time, for minutes, until one of us was dead. We had a lot in common, as all brothers have; each of us was seeking, would soon seek more actively as fatigue set in and mistakes were made, the other's death.

Below in the street a last car door slammed; I suppose one of the guests hadn't been in terribly good shape for driving, was now being escorted home. The staff would be clearing up the ballroom by now, the remains of the caviar and the boar's head, the roast goose, the dirty glasses, the single white glove dropped by one of the women, perhaps, a ballpoint pen or two, a visiting-card, while in the -

No you fucking well don't.

He'd tried again, testing me.

While in the rest of the hotel Vishinsky would be conducting the search, the manager with him to placate any guests who were trying to sleep. They would take it floor by floor, starting on the ground and gradually coming higher. It hadn't occurred to this man lying here with me that the most he had to do was hold me off until there were footsteps on the stairs; if it had occurred to him he wouldn't have tried those moves.

'What's your name?' I asked him, hardly enough breath to spare but as I say it's always important.

He didn't answer.

The cold air pressed against our faces, the chill of the sweat clammy, beginning to itch. I hadn't made a move yet because when I made it I wanted it to succeed, to kill. There'd be no chance of letting him live: I had to get to the roof of the other building after I'd buried him under the snow.

I didn't know how much longer I had before another guard came up here to look around. Ten minutes? Five? None?

Watch the doorway.

He had callouses, this man, along the sword-edge, harder on the right hand. He liked chopping bricks, to show how strong he was – correction – to prove to himself howstrong he was: these cocky super jocks always have the seed in them of self-doubt.

He made a move and I parried it but he was desperate and managed to bring an elbow strike to graze my head and followed through with a knee strike and I had to roll face down and try for his eyes but he got a hand free and found the trigger of the rifle and put out a short burst before I could do anything, blinding flash and the stink of cordite, the eyes having to accommodate now, the thought process having to re-establish itself after the shock of the percussion, time needed, milliseconds, before I could react and hook for his eyes to inflict pain, got it and found leverage enough to drive a half-fist into his throat with the necessary force to kill as he too rolled and found the trigger again but I was there first and broke his finger and now he began calling out or trying to, but the strike had broken the cartilage in his throat and internal haemorrhage was beginning and he couldn't manage any kind of sound that could raise the alarm.

Reassess time factor: shots were heard at all hours of the night in this city and under the open sky there'd be no directional acoustics to guide the guards in the streets below – that short burst could have come from anywhere. But it would have sounded in the stairwell through the doorway and I got the guard's wallet and put it away and pulled his padded jacket off because I'd checked my sable coat in the hotel lobby when I'd arrived tonight.

Liquid sounds now from my dying brother, requiescat in pace, the soft ululation of the blood blocking the windpipe as I got him into my arms to avoid leaving tracks, carried him across the roof and laid him down and covered him with snow, kicking it loose and scooping it until my hands were raw and gradually his body took on the form of its own white crystalline grave; then I left him and crossed to the emergency stairs and listened, heard nothing, closed the metal door and went to the parapet that faced the next building, didn't look down this time into the narrow gap, looked across to the parapet opposite, didn't think again of the conditions: frozen snow with only pale moonlight to work with, the shadows deceptive, the distance too great for any kind of confidence, the muscles sluggish because of the cold, the chances of success dauntingly thin.