High above, on the 40th floor, the first two residents were preparing to leave.

All day Anthony Royal and his wife had been packing. After lunch in the deserted restaurant on the 35th floor they returned to their apartment, where Royal spent what he knew would be his last hours in the high-rise closing down his design studio. In no hurry to leave, now that the moment had come for them to abandon the building, Royal deliberately took his time over this last ritual task.

The air-conditioning had ceased to function, and the absence of its vague familiar hum-once a source of minor irritation-made Royal restless. However reluctantly, he was now forced to recognize what he had been trying to repress for the past month, despite the evidence of his eyes. This huge building he had helped to design was moribund, its vital functions fading one by one-the water-pressure falling as the pumps faltered, the electrical sub-stations on each floor switching themselves off, the elevators stranded in their shafts.

As if in sympathy, the old injuries to his legs and back had begun to keen again. Royal leaned against his drawing-stand, feeling the pain radiate upwards from his knees into his groin. Gripping the chromium cane, he left the studio and moved among the tables and armchairs in the drawing-room, each shrouded in its dust-sheet. In the year since his accident he had found that constant exercise alone held back the pain, and he missed the games of squash with Robert Laing. Like his own physicians, Laing had told him that the injuries sustained in car-crashes took a great deal of time to heal, but Royal recently had begun to suspect that these wounds were playing a devious role of their own.

The three suitcases he had packed that morning stood ready in the hall. Royal stared down at them, for a moment hoping that they belonged to someone else. The cases had never been used, and the prominent part they would soon play in his personal Dunkirk only rubbed in the humiliation.

Royal returned to the studio and continued to take down the architectural drawings and design studies pinned to the walls. This small office in a converted bedroom he had used for his work on the development project, and the collection of books and blueprints, photographs and drawing-boards, originally intended to give a sense of purpose to his convalescence, had soon become a kind of private museum. The majority of the plans and design studies had been superseded by his colleagues after the accident, but in a strange way these old frontal elevations of the concert-hall and television studios, like the photograph of himself standing on the roof of the high-rise on hand-over day, described a more real world than the building which he was now about to abandon.

The decision to leave their apartment, already postponed for too long, had been difficult to take. For all his professional identification with the high-rise as one of its architects, Royal's contribution had been minor, but sadly for him had concerned those very sections which had borne the brunt of the residents' hostility-the 10th-floor concourse, the junior school, the observation roof with its children's sculpture-garden, and the furnishing and design of the elevator lobbies. Royal had gone to immense care in the choice of wall surfaces, now covered by thousands of aerosolled obscenities. It was stupid of him, perhaps, but it was difficult not to take them personally, particularly as he was only too aware of his neighbours' hostility towards him-the chromium cane and white alsatian were no longer theatrical props.

In principle, the mutiny of these well-to-do professional people against the building they had collectively purchased was no different from the dozens of well-documented revolts by working-class tenants against municipal tower-blocks that had taken place at frequent intervals during the post-war years. But once again Royal had found himself reacting personally to these acts of vandalism. The breakdown of the building as a social structure was a rebellion against himself, so much so that in the early days after the jeweller's unexplained death he expected to be physically attacked.

Later, however, the collapse of the high-rise began to strengthen his will to win through. The testing of the building he had helped to design was a testing of himself. Above all, he became aware that a new social order was beginning to emerge around him. Royal was certain that a rigid hierarchy of some kind was the key to the elusive success of these huge buildings. As he often pointed out to Anne, office blocks containing as many as thirty thousand workers functioned smoothly for decades thanks to a social hierarchy as rigid and as formalized as an anthill's, with an incidence of crime, social unrest, and petty misdemeanours that was virtually nil. The confused but unmistakable emergence of this new social order-apparently based on small tribal enclaves-fascinated Royal. To begin with, he had been determined to stay on, come what may and whatever the hostility directed against him, in the hope of acting as its midwife. In fact, this alone had stopped him from notifying his former colleagues of the mounting chaos within the building. As he told himself repeatedly, the present breakdown of the high-rise might well mark its success rather than its failure. Without realizing it, he had given these people a means of escaping into a new life, and a pattern of social organization that would become the paradigm of all future high-rise blocks.

But these dreams of helping the two thousand residents towards their new Jerusalem meant nothing to Anne. As the air-conditioning and electricity supply began to fail, and it became dangerous to move unaccompanied around the building, she told Royal that they were leaving. Playing on Royal's concern for her, and his own feelings of guilt about the breakdown of the high-rise, she soon persuaded him that they must go.

Curious to see how she was getting on with her packing, Royal walked into his wife's bedroom. Two wardrobe trunks, and a selection of small and large suitcases, jewellery boxes and vanity cases lay open on the floor and dressing-table like a luggage store display. Anne was packing, or unpacking, one of the cases in front of the dressing-table mirror. Recently, Royal had noticed that she deliberately surrounded herself with mirrors, as if this replication of herself gave her some kind of security. Anne had always taken for granted a naturally deferential world, and the last few weeks, even in the comparative safety of this penthouse apartment, she had found more and more trying. The childlike strains in her character had begun to come out again, as if she was suiting her behaviour to the over-extended mad-hatter's tea-party that she had been forced to attend like a reluctant Alice. The journey down to the 35th-floor restaurant had become a daily ordeal, and only the prospect of leaving the apartment building for good had kept her going.

She stood up and embraced Royal. As usual, without thinking, she touched the scars on his forehead with her lips, as if trying to read a digest of the twenty-five years that separated them, a key to that part of Royal's life she had never known. As he recovered from the accident, sitting in the windows of the penthouse or exercising on the callisthenics machine, he had noticed how much his wounds had intrigued her.

"What a mess." She gazed down hopefully at the jumble of suitcases. "I'll be about an hour-have you called the taxi?"

"We'll need at least two. They refuse to wait now-there's no point in calling them until we're on the doorstep."

Both their own cars, parked in the line nearest the building, had been damaged by the tenants below, their windscreens knocked out by falling bottles.

Anne returned to her packing. "The important thing is that we're going. We should have left a month ago when I wanted to. Why anyone stays on here I can't imagine."

"Anne, we're leaving …"

"At last-and why has no one called the police? Or complained to the owners?"

"We are the owners." Royal turned his head away from her, his smile of affection stiffening. Through the windows he watched the light fading across the curtain-walling of the nearby high-rises. Inevitably, he had always taken Anne's criticisms as a comment on himself.

As Royal knew now, his young wife would never be happy in the special atmosphere of the high-rise. The only daughter of a provincial industrialist, she had been brought up in the insulated world of a large country house, a finicky copy of a Loire chateau maintained by a staff of servants in the full-blown nineteenth-century manner. In the apartment building, by contrast, the servants who waited on her were an invisible army of thermostats and humidity sensors, computerized elevator route-switches and over-riders, playing their parts in a far more sophisticated and abstract version of the master-servant relationship. However, in Anne's world it was not only necessary for work to be done, but be seen to be done. The steady breakdown of the building's services, and the confrontation between the rival groups of tenants, had been too much for her, playing on her huge sense of insecurity, all her long-ingrained upper-class uncertainties about maintaining her superior place in the world. The present troubles in the apartment block had exposed these mercilessly. When he had first met her, Royal had taken for granted her absolute self-confidence, but in fact the reverse was true-far from being sure of herself, Anne needed constantly to re-establish her position on the top rung of the ladder. By comparison, the professional people around her, who had achieved everything as a result of their own talents, were models of self-assurance.

When they first moved into the high-rise as its first tenants, they had both intended the apartment to be no more than a pied a terre , conveniently close to Royal's work on the development project. As soon as they found a house in London they would leave. But Royal noticed that he continued to postpone any decision to move out. He was intrigued by life in this vertical township, and by the kind of people attracted to its smooth functionalism. As the first tenant, and owner of the best and highest apartment, he felt himself to be lord of the manor-borrowing a phrase he disliked from Anne's rule book. His sense of physical superiority as a sometime amateur tennis champion-a minor hard-courts title, though no less impressive for that-had inevitably slackened with the passage of years, but in a way had been rekindled by the presence of so many people directly below him, on the shoulders of whose far more modest dwellings his own rested securely.