'Alone?'

'Yes. Again, you'll be fully briefed. You should also know at this point that the mission is to be strictly confined to the intelligence community in London, with not the slightest involvement with the Foreign Office or overseas embassies — unless the circumstances of the mission call for it. But if you accepted the assignment you would have the full resources of the Bureau at your command, under my personal and constant supervision.'

He stopped short of where the other men stood waiting, and faced me with his head turned slightly to the right, his eyes trapping light from a pilot lamp overhead. 'This, I think, is as much as you need to know at this stage, but I'm prepared to answer any question, providing it's of the most vital consequence.'

He wouldn't give me long. He'd told me all he was going to tell me, because if I refused the mission he didn't want a critical mass of information loose in my head: any agent at any time can be got at and picked clean, even between assignments, if someone suspects he's loaded with some kind of product. Until I accepted this one I'd be told nothing more.

There was only one question I could ask Shepley that would give me an idea how big this assignment was, and whether I should even look at it. 'It wasn't Yasolev,' I said, 'who made the approach off his own bat. He's not big enough. So who was it?'

'General-Secretary Mikhail Gorbachev.'

We inched forward again, the lamps sliding past the tinted windows of the Mercedes and throwing shadows across the driver's head. He hadn't spoken until a few minutes before, when we'd reached the checkpoint. 'We could go through the official-traffic lane, but we'd call more attention. Is that all right with you, sir?'

I'd said yes. Shepley had told me there'd be no delay getting through — no one would check us — but I wanted to attract as little notice as I could.

The driver had fallen silent again. The figures outside looked almost faceless through the smoked windows and my dark glasses; their voices were faint. It was four in the morning, a dead hour, with only half a dozen vehicles ahead of us.

We moved again, the engine's note soft, muted, the lights on the facia glowing.

Are they going to interrogate us?

She was shivering, curled against me, her woollen coat soaked from melted snow. One of the guards outside the hut was coughing again, the cold air freezing his lungs.

Not you, no. You don't know enough.

Margaret. Margaret Someone. Jennings? Fenning? Something with 'ing' at the end. In three years you can forget your own name, in this trade.

'Which road are we taking?'

The driver turned his head slightly, his eyes in the mirror. 'Through Barnau. Be an hour, maybe. A bit more.'

Car doors slammed ahead of us. Peaked caps, the angular roofs of low buildings, the silhouette of an alarm siren against the haze beyond.

She can go, the guard said, coming in, his face muffled in wool against the cold. Come on — move! He kicked her foot.

She turned her head to look at me, but I said in English, Don't question it. Get going.

The Mercedes was new, smelling of leather, not the kind of transport you normally get from the Bureau. And a uniformed driver. Perhaps not the Bureau, then, perhaps by courtesy of the General-Secretary. I didn't think this was going to be my kind of thing, too political, too distinguished, not the job for a ferret. But I'd nothing to lose.

We inched forward again, and the peaked caps gathered immediately outside, turned towards a civilian with papers in his gloved hand, orders.

But what about you?

I knew she'd say that.

I can look after myself. Get going, for Christ's sake, before they change their minds.

She struggled to her feet, giving me a last look, her eyes frightened but for me now, not for herself. It makes me feel awful.

I jerked a hand. Just get going.

The voices outside the car had stopped, and we moved on again, this time accelerating through barriers.

'Is that it?'

'Yes, sir.'

I looked at the clock on the facia. An hour, maybe a bit more, would bring us to the rendezvous just before dawn.

She lurched to the door of the hut, her legs cramped from the long night, the long waiting, and when she'd gone I asked the guard in Russian, On whose orders?

Comrade Colonel Yasolev's.

I put away the sunglasses, and the environment took on brightness, colour: a steady 3,500 rpm on the revolution-counter, the star mascot outlined against the wash of the headlights, a signpost sliding by: Bernau 22km, Eberswalde 47km.

He'd known, of course, Comrade Colonel Yasolev, that it wouldn't have been worth putting her under the light, wearing her down, she knew almost nothing; she'd been a contact for the frontier line pulled in at the last minute to cover a gap in communications; she hadn't even been briefed, just told to get there and wait for instructions. She'd only made contact with me as a matter of routine to establish liaison, and that was when they'd caught us, holed up under the floorboards of a rotting wharf with our hands and faces darkened with some soot I'd scraped from a boiler and one of her feet shoeless, which was how they'd got on to us: the other shoe had come off when she'd run headlong for cover.

And what would have been the point, anyway, in their putting her on trial and sending her to a penal settlement? Another mouth to feed, however many mailbags she sewed, however much wood she hauled. But that wasn't why he'd let her go. It had been a, gesture. I'd got to know Comrade Colonel Yasolev quite well during the three weeks of the mission and I'd picked up a few things about him from the KGB lieutenant I'd pinned down and grilled in a cellar in Klimovsk: Yasolev was the son of a Soviet Army general, and a graduate of the Moscow State University with a degree in Japanese and some post-graduate work put in at the Institute of Oriental Studies. In 1985 he'd served undercover for the KGB as Bureau Chief of the Soviet magazine New Times in Tokyo; then he'd been brought back to his homeland to run clandestine operations from Moscow, trapping Western spooks for the counterespionage division and pulling in Price-Baker, Johnson of the Company, Foxwell and Grant and Bellows from the SIS, all of them senior people, most of them now in the Gulag, Foxwell dead and Johnson exchanged for Pitovsky a year ago.

But the most interesting thing I'd picked up from the lieutenant in Klimovsk was that Yasolev was a chivalrous man, enlightened, though not soft: He bullied the prosecutors for the maximum term in every case, and got it. He also had a daughter, Ludmila, who was now studying at the Academy of Science in Moscow. All right, for Margaret read Ludmila; they'd be about the same age or at least the same generation. And reading a little closer, between the lines, yes, his casual act of clemency had been subjective, self-indulgent; but the fact remained that I'd been there in that freezing hut and I'd seen her small huddled figure go lurching through the doorway to freedom and when the guard had told me whose the orders were I'd felt a moment of warmth in that bitter cold and had been astonished by it, because in this trade the smallest act of charity can have the force of revelation.

There'd been a postcard, a month ago, from East Grinstead, just signed 'Margaret'; she still kept in touch.

'About another ten minutes,' the driver said.

It was still dark.

'Are you armed?'

His eyes flicked to look at me in the mirror. 'No, sir. Those were my instructions. You're not expecting any kind of trouble?'

'No.' If he'd had anything on him I'd have told him to throw it away. The rendezvous is to be made, Shepley had said, according to the strict protocol of a diplomatic exchange of courtesies, and both sides understand that. Otherwise I'd never have agreed to go through the Wall in the wrong direction, not on your bloody life.