I don't like heights. I'd seen a man go down, once, from the twenty-first floor of a construction site. They say you scream but you don't. They call it going down the hole, the construction workers, and when one of them does it the rest of them are told to go home for the day because it's unnerving and therefore dangerous.

One foot, then the other. The ankles had started aching and I wanted to angle the feet the other way but it would mean shifting the body's equilibrium and the nerves were already under stress; I was beginning to feel that the wall had started leaning towards the street, and the ledge tilting. This was normal: fear begets illusion; but it would have to be dealt with, combatted.

Like a crab. Moving like a crab along the wall. A dull ache had started at the top of the spine. I was keeping my head to one side, to the left, the way I was moving, because when I turned it to the right the building across the street swung across the vision field and affected the sense of balance.

A captain of the HUA?

I was now certain that it would have been safer to stay in the room and face it out.

What department are you, Captain?

It would have been dangerous to let them put me under interrogation but less dangerous than this dizzying height in this killing cold.

This is Commandant Melnichenko, Adviser to the Airforce Directorate. I have a Captain Kurt Heidecker here, with the HUA, service number D/435-05. Is he known in your department?

A gust of wind came and my shoulders met the wall and I froze and contracted the leg muscles and waited, for a moment sickened. If the wind got stronger in the night there wouldn't be a hope in hell: it'd blow me off the building.

He's not known in your department?

And there would have been no explanation he would have accepted when he asked what I was doing in his office; compared with a commandant of Soviet Military Intelligence a captain of the HUA had no authority.

But there would have at least been a chance, even in the hands of the GRU. I couldn't have given them Yasolev's name because Yasolev was using me to infiltrate Trumpeter and Melnichenko had a file on that operation in his office and he would have had me shot, just as someone had had Lena Pabst shot. The situation here in East Berlin forty-eight hours before the arrival of the General-Secretary of the USSR was ultra-sensitive. Yasolev was here on a secret assignment known only to his immediate cell within his department; he'd made it a condition of our liaison that I didn't expose either him or his assignment to East German Intelligence; and the GRU had an adviser buried in the Airforce's HQ with a file on Trumpeter in his care.

In addition there was the London connection, and if I ever got close to blowing my own cover the Bureau would expect me to use the capsule and I would do that.

Window.

I'd been watching it for minutes now, trying to see if there were any chance of using it. When I'd got out of Room 60 I'd left the window open an inch so that I could have climbed back inside after they'd gone, and it was conceivable that another window somewhere had been left open by mistake and I could — watch it, you're losing rationality. It was not conceivable that any window of this building had been left open in winter conditions with the heating system going full blast.

Glass. Perfectly smooth glass and a frame less than an inch proud of the wall, drawing blank so move on, keep moving. Given a wider ledge, wider by only a few inches, I might have jabbed an elbow against the glass and smashed it and gone through. On this ledge there wasn't enough room for leverage.

Wind gust and it tugged at me and I froze and waited and longed to shut my eyes but without a visual reference the balance would have gone. The gust had rocked me sideways a little before I'd had a chance to contract the muscles, and the buildings opposite tilted back and that was when the vertigo began, the real thing, and for the first time I realised there wasn't necessarily a chance of reaching the corner and making the turn and finding some kind of purchase on the next face of the building.

Keep still.

The street steadied and held and then shifted again, and all I could do was try to keep still, but vertigo is not just a sensation, not just a fear of heights: it's the primitive fear of falling, of dying, of taking time to die, of being cut off from the safety we have known since we crawled across that solid floor and began to know on the subconscious level that it would always be like this; there would always be the safety of solidity beneath us, the arms of the Earth Mother.

Keep still.

But it was here to stay, now, the vertigo, and I was keeping still because I couldn't move any more, unless I could deal with the enemy within the gates, within the mind.

Breathe deeply, slowly, call upon prana.

The consciousness of known values was diminishing, slipping away, and soon there was no mission to be accomplished, no action to be accounted for; London was the shred of a thought, a name for a place where a man called Shepley lived, had once lived, in the past. Another man, with the name of Melnichenko, floated through my mind as a figment, a ghost seen moving through a hall of mirrors, of reflections, as reality seeped away and took with it the demands of normal life, that I should somehow make my way along this ledge and find a place where I could be safe, and pick up a telephone and say, I am safe now, I am safe.

Life had become refined and narrowed down, with the trivia of earlier ambitions stripped away and leaving the stark immediacy of the present. The world had shrunk to a few square inches of concrete where I stood, where this organism stood with its feet at the precise angle at which they could best sustain life, with its splayed fingers touching the mass of concrete behind its body for the purpose of tactile orientation but with the knowledge that any slight pressure on the wall would begin the mechanical process that would eventually extinguish life, as the body was tilted forward and poised at an angle above the void, an angle from which it could not now return, but from which it must tilt progressively forward until the feet lost the security of the ledge beneath them and followed the body as it began curving over with the weight of the head turning it in the air as it gathered speed and plunged directly to the earth below as the mind played out the drama of the occasion, first experiencing the swift onset of terror as the windrush moved through the hair and pressed against the eyes, the terror of annihilation, of obliteration as the details of the street grew larger and more defined as if seen through the zoom lens of a camera, and then, following the terror, the experience of rage, of rage against the gods, against the fates, bringing to the organism a semblance of identity after its loss in the helplessness of the terror, and then, following the rage, euphoria, easing all travail away and leaving in its place the onset of spiritual peace, of acceptance, of an understanding that would know nothing of the body's gross concerns of physical death as the head hit the ground and the brains were smashed from the skull and the arms were flung out and the stillness came, the inertness, the mutation from creature to object, to chemicals, while -

Gust of wind -

Oh God -

Stay… stay… hold still…

Hold still, and fix the eyes on the window there, on the window across the street, so as to keep stillness in the mind through the eyes' reference, hold still and wait it out, with the feet braced and pressing forward by infinite degrees until the shoulders feel the presence of the wall and all movement ceases and the wind's sudden tugging dies away, dies away.