On the south coast, the snow lay thinner and patchier, but the wind came off the grey sea like a frozen scythe. Maxim and Chris tramped the pebble bank at the top of the beach, their feet shifting and sliding, stopping to pick up the smoothest stones and fling them into the waves. Hunger, sex and throwing stones into water were the three primitive drives that had made the human race what it is, Maxim decided.

At ten years old, Chris had grown sideways as much as upwards: he was now a miniature Welsh fly-half. Indeed, there was something of the original Celts about his long dark hair and his pale skin – but the eyes, when he turned a sudden direct stare on you, were the golden-dark of Jenny's.

And he mustn't know, Maxim thought. I must see only him in his own eyes, nobody else.

"Daddy," Chris asked, "when are you going back to London?"

"When somebody rings up. When they want me."

"Is it very secret, what you're doing?"

"Not very, no," Maxim said glibly. "I'm there to answer military questions – if I can. And all military things are at least partly secret."

"Do you see the Prime Minister all the time?"

"Not to speak to. He's around, but I usually work to one of his private secretaries, George Harbinger. I don't think you'd better mention his name around school, by the way."

"Of course I won't." Chris hunched his shoulders~ in the inevitable plastic rally jacket – and trudged on, frowning over what he would say next. "Daddy – what sort of aeroplane was Mummy in when she crashed?"

"A Short Skyvan. Very square-shaped, twin engines, twin tails, high wing, fixed undercarriage… don't you know it?"

Chris nodded; he could identify most modern aircraft from the swamp of books and magazines in his bedroom. "I thought it was a Skyvan."

"Why did you ask, then?"

"Some of the boys at school… they said they didn't believe Mummy was really dead, that she'd just gone away and left us. I thought if I could be sure what aeroplane it was, they'd believe me."

I will kill those boys, Maxim thought. One by one I will pick them up and beat their little heads to a pulp and then it won't matter what they believed…

He realised how fast he was walking, crunching ahead of Chris at a Rifle pace. He slowed. It isn't cruelty, he thought, it's just that a broken marriage is something all these kids know about, and death is something that only happens on TV. Particularly in a blown-up aeroplane. He stopped and threw three stones, trying to cut them through the crests of the breaking waves.

"I saw the aeroplane crash," he said in a flat voice.

"Yes, Daddy," Chris said. "So you're quite sure she won't comeback?"

If they were here I would kill them, for giving Chris such a terribly false hope.

"No," he said. "No chance. It's just you and me."

He put his arm around the boy's shoulders and they walked back through a gap in the ramshackle bathing huts onto the pebble-strewn seafront road and Maxim's car.

After a while, Chris asked: "Do you have to keep on taking exams in the Army?"

"Yes – them, or something like them."

"Ugh."

"Well, you could always become a tramp, or even go into the Air Force."

"Daddy!"

They were laughing by the time they reached Maxim's parents' house. There was a message to ring George.

The Massons' bungalow was a rambling affair thrown together by a speculative jerry-builder just after the First World War. It had been built for summers of tennis, cocktails and open sports cars. Under the snow, fifty years later, it looked like a group of Army huts that had melted together. Maxim drove cautiously up the thirty yards of driveway, already squashed into rutted ice by other vehicles. At the top there were four parked cars and a plain van. He just squeezed into a space beside the rickety wooden garage that was two cars long instead of wide. Odd, that.

It was also odd that there didn't seem to be a front door, just french windows that had curtains drawn across them. But a uniformed policeman hurried out of a kitchen door wanting identification. Maxim took time finding his ID card, looking around at the perfect snow on the tennis lawn, at the bulging laurels and evergreen shrubbery.

Agnes was sitting at the kitchen table, which was covered in mugs, milk bottles, cups and teapots. She still had her sheepskin jacket on, and her face looked stale. "Hello, our 'Arry. Do you want a cuppa as well?"

"If it's going," Maxim said automatically, and sat down, unbuttoning his car coat. She poured him a mug of tea. The whole room, which wasn't very big, looked slightly askew. Somebody had moved the refrigerator, the dishwasher, gas stove and a cupboard and not quite got them back in line. Deeper into the house, he could hear mutterings and tappings as the searchers moved on.

Agnes passed him a mug. "In a while they'll be testing the floorboards and stripping paper off the walls. Some of the plaster, too."

"Have they found anything?"

"Enough to be sure he was on the take from Moscow. What did George tell you?"

"Just that he was the man Zuzana Kindl was telling me about."

"Yes." Agnes gave him a brief history of Rex Masson's work at MI5. "He must have handed the file back to the bad fairies and jumped off that same night while you were explaining yourself to the Special Branch in Buckinghamshire. He'd have a crash escape all planned…" she shrugged inside her sheepskin jacket, which barely moved. To Maxim the house seemed quite warm, and he wondered briefly who paid for it now. And for the stripped wallpaper and plaster. Whose house was it, now?

He sipped the lukewarm sweet tea. "We don't know how or where?"

"The first flight he could get. Berlin or Vienna for choice, but any capital with a sizeable Russian embassy. There's no point in trying to find out. In six months time, when they've taught him to sit up and beg nicely, he'll surface in Moscow and give a press conference telling how sickened he was with the work he had to do for his fascist imperialist bosses here. And then he'll settle down in a nice little concrete flat and a small summer dacha outside Moscow – not too far outside – with a Party card so his wife can go to the head of the queues and he can buy the latest Juilliard Quartets at the foreign currency store and then just sit there and drink himself to death. Because that's all he's got left. All he's left himself."

She sounded very vicious.

"How old was he?" Maxim asked, then wondered why he'd said 'was' about a man who was presumably still alive.

Agnes gave him a tired smile. "Just the right generation, maybe the last of them. He was up at Oxford in the late forties, when Moscow still had some sex appeal. With the kids at the universities today, you couldn't give them Russian communism with a free pound of Mexican grass. They're into Chile or black Africa… I suppose even China's unfashionable now that they're playing footsie with America. More tea?"

"No thanks. What are you doing here when you're not playing mother?"

"Keeping an eye on the service's interests and telling George what's going on. I assume you'll do that now."

"I don't know. Is there anything going on?"

"Go and have a look. One of the coppers says he knows you."

As Maxim turned away, Agnes added: "Have you got your gun this time?"

"No. Why?"

"Oh, nothing," She grinned privately into her teacup.

Beyond the kitchen was a badly-lit corridor with doors on both sides and two men rolling up the carpet. But the mutterings seemed to come from an open door opposite. Maxim went through a dining room with heavy tables and chairs all pushed out of place, and opened a door on the far side.

It was a big low-ceilinged room, the one with the french windows at the front end, and windows on both side walls. The fourth wall was mostly a wide fireplace with a basket grate and the ashes of a log fire. It was rather cluttered, originally with knick-knacks of furniture – small tables, pouffes, standing lamps along with several soft chairs, a sofa, an upright piano – but now also with five plain-clothes policemen. One of them got up from where he'd been poking the floor beside the piano and came towards Maxim grinning and holding out his hand.