The huge iron scoop slammed down and black gas rose. 'Back!' a man shouted, waving, and I reversed the truck again.

The snow plough moved forward another ten yards, its diesel roaring under full throttle as it lifted another ton of snow and swung it clear of the road. The exhaust gas drifted past us like a smoke screen and I felt safe for a moment, because they would have known by now that the barn hadn't gone up and they might be short of time and bring a gun in. It wasn't certain they'd do that. You've got to take calculated risks.

The man waved us forward again, standing back this time to let us through the gap: they were clearing the intersection, routing us through a detour.

Karasov sat beside me, leaning his head back against the seat and gazing through the windscreen with his eyes narrowed. He had the look of a man in a tumbril on his way to the guillotine, slack with despair.

'Was it a bomb?' he had asked me a little time ago. 'A bomb he was talking about, when he spoke of a 'toy'?'

'Yes.' He might as well know.

'How did you find it?'

'Bit of luck.'

I didn't tell him it was still here under the driving-seat. He would have got out and walked.

We ground along in first gear, shunting between a coal truck and a beaten-up Zhiguli van.

I didn't think they'd bring a gun in because they could have done that before: they could have dropped us as we'd come out of the cave. There were plenty of other ways, quieter ways, less public. But it was a calculated risk and every time we shunted to a halt I felt my head settling instinctively onto the top of the spine and my shoulders rising into the primeval startle attitude, because this was when they'd steady the aim and fire, when we were stationary. They would have to shoot twice or use two guns unless it was only Karasov they'd been trying to kill in the barn, expecting him to climb into the truck with me before I started the engine. My death could have been planned as incidental but that wasn't certain either: the Rinker cell could have reasons for taking me down, putting me out of their way.

The windscreen was filthy but I hadn't wiped it clean before we'd started off; we wouldn't be hitting up any kind of speed and it gave us a degree — just a degree — of safety: they'd have to judge where our heads were if they meant to station a gun somewhere in front of us along the road.

'Then they'll try again,' Karasov said suddenly. I didn't realize he'd been all that time thinking it out; there were a thousand things on his mind, I knew that. But I didn't know what they were.

'Not necessarily.' We halted again, and my head settled.

'Of course they will. When they know the bomb didn't kill us, they'll try again.'

'They wouldn't have let us get this far, don't worry.'

He didn't say anything to that, but put a hand into the pocket of his dark woollen coat and held something out to me. I glanced down and saw a cassette tape.

'Take it,' he said.

I put it into my pocket. 'What is it?'

'The second tape.'

We were stuck again by another snow plough and I turned off the engine so that I could hear better: not only his words but the tone. He was going to talk now. He was going to tell me why he was so deathly afraid. The sleeper had waked, now he would talk.

A second tape?

I didn't turn my head to look at him. It was already in my mind that what he would say to me would be in the form of a confessional. I'd sensed an element of guilt in this man before.

'What's on it, Karasov?'

'It's a duplicate of the one you took to London.'

I remembered the debris pattering down in Eaton Place after the two boffins had climbed into their car.

It had been for nothing, then. There was another tape.

A man's face was at the window suddenly and I looked at it through the glass. He was saying something. His breath steamed as he waved his hand, shouting now. I wound the window down. He wasn't an agent; he was a farmer, his face weathered into a grizzled brick-red mask and his eyes sunk into their sockets, rheumy with the cold.

'I'm out of petrol! Can you spare me a drop, comrade?'

I could feel Karasov's fear beside me. He was going to be like this all the way to the railway station, all the way to the coast.

"I'm almost out myself,' I told the man. 'That's why I've switched off the engine.'

He threw up his arms and trudged forward through the snow to talk to the driver in the truck. I wound the window up and asked Karasov, 'Why did you take a duplicate?'

It was a long time before he answered. 'For the others.'

The man's voice came back to us as he shouted to the driver in front. Somewhere on the road ahead I could see the shape of another mechanical scoop clearing the snow. I gave Karasov time, but he wanted me to drag it out of him like a priest in the confession box. Guilt never comes out in a hurry.

'What others?'

'The Chinese.'

It was like a bullet coming through the windscreen. I hadn't been ready for it.

'Go on,' I told him. He wanted goading.

'I-' and that was all for another minute. I didn't prompt him again, because he'd hear fury in my voice and that would frighten him off altogether. He wouldn't know that the fury wasn't against him but against myself, against Fane, against Croder. None of us had known and, we should have known. We should have known that an international incident big enough to threaten the summit conference would inevitably involve triangle diplomacy and the China card.

'I–I've been giving product to them for a long time now,' Karasov said.

Mother of God.

''How long?

I felt him jerk in fear as his head swung to look at me. He'd heard it: the fury. I would have to do better than this but by Jesus Christ I was sitting here in a stinking farm truck with our run to the coast blocked off by snow and the objective for the mission sitting beside me and telling me he'd been working for both major intelligence networks, East and West, for a long time, eight days into Northlight and already five on the deathroll and a live bomb under my legs and someone out there putting the windscreen into the crosshairs or signalling ahead of us to get a trap set or coming up from behind us like the man who was out of petrol and there was nothing I could do about it until I could get this bastard to the frontier and take him to London and leave him there to spill his guts all over Croder's debriefing desk and then I was going to ask questions, an awful lot of questions about the man running our Murmansk cell and why the hell he'd let his sleeper go on working for London and Peking without checking on his product and his couriers and his contacts and his communications because somewhere he could have been caught, could have been seen slipping a package into a furtive hand in the shadows of a crowded bar or on a bus or in a brothel or wherever they'd set up their drop, somewhere they could have tapped a line or checked a crossed signal or questioned the travel patterns or stood close to a talker, catching a hint of smoke on the air, a whiff of something burning.

'What?'

'Years,' he was saying. 'Years.'

I didn't answer him until I'd got control again. Keep cool, yes, absolutely, nothing to get into a tis-was over, just sitting here thinking I'm working exclusively in the Soviet zone and all the time there's a Chinese cracker rigged to go off, love from Peking, bit of a joke really, something funny happened to me on my way to Murmansk, this one's going to kill you.

That, too, yes.

'Have you been giving them everything?'

He waited until I'd dragged the gears in: we'd started moving again. 'Not everything. Only the stuff they'd be interested in.'

'Only the stuff they'd buy?' Rather rude, that, yes, but I wasn't really in the mood for good manners.