This was a breakthrough, and not the last. Clearly there was a deep undercurrent of fatigue. By the day of Dr Edwards' return, Ryan estimated that one in ten of the militia fighters was wearing the blue helmet or beret. Firefights still shook the night sky, but the bursts of gunfire seemed more isolated.

'Ryan, it's scarcely credible,' Dr Edwards told him when they met at the UN post near the harbour. He pointed to the map marked with a maze of boundary lines and fortified positions. 'Today there hasn't been a single major incident along the Green Line. North of the airport there's even a de facto ceasefire between the Fundamentalists and the Nationalists.'

Ryan was staring at the sea, where a party of Christian soldiers were swimming from a diving raft. The UN guardships were close inshore, no longer worried about drawing fire. Without meaning to dwell on the past, Ryan said: 'Angel and I went sailing there.'

'And you'll go sailing again, with Nazar and Arkady.' Dr Edwards seized his shoulders. 'Ryan, you've brought off a miracle!'

'Well...' Ryan felt unsure of his own emotions, like someone who has just won the largest prize in a lottery. The UN truck parked in the sun was loaded with crates of blue uniforms, berets and helmets. Permission had been granted for the formation of a Volunteer UN Force recruited from the militias. The volunteers would serve in their own platoons, but be unarmed and take no part in any fighting, unless their lives were threatened. The prospect of a permanent peace was at last in sight.

Only six weeks after Ryan had first donned the blue helmet, an unbroken ceasefire reigned over Beirut. Everywhere the guns were silent. Sitting beside Captain Gomez as they toured the city by jeep, Ryan marvelled at the transformation. Unarmed soldiers lounged on the steps of the Hilton, groups of oncebitter enemies fraternised on the terrace of the Parliament building. Shutters were opening on the stores along the Green Line, and there was even a modest street market in the hallway of the Post Office. Children had emerged from their basement hideaways and played among the burntout cars. Many of the women guerrillas had exchanged their combat fatigues for bright print dresses, a first taste of the glamour and chic for which the city had once been renowned.

Even Lieutenant Valentina now stalked about in a black leather skirt and vivid lipstick jacket, blue beret worn rakishly over an elegant chignon.

As they passed her command post Captain Gomez stopped the jeep. He doffed his blue helmet in a gesture of respect. 'My God! Isn't that the last word, Ryan?'

'It certainly is, captain,' Ryan agreed devoutly. 'How do I even dare approach her?'

'What?' Gomez followed Ryan's awestruck gaze. 'Not Lieutenant Valentjna she'll eat you for breakfast. I'm talking about the soccer match this afternoon.'

He pointed to the large poster recently pasted over the cracked windows of the nearby Holiday Inn. A soccer match between the Republican and Nationalist teams would take place at three o'clock in the stadium, the first game in the newly formed Beirut Football League.

"Tomorrow Christians versus Fundamentalists. RefereeColonel Mugabe of the International Brigade." That should be highscoring...' Blue helmet in hand, Gomez climbed from the jeep and strolled over to the poster.

Ryan, meanwhile, was staring at Lieutenant Valentina. Out of uniform she seemed even more magnificent, her Uzi machinepistol slung over her shoulder like a fashion accessory. Taking his courage in both hands, Ryan stepped into the street and walked towards her. She could eat him for breakfast, of course, and happily lunch and supper as well.

The lieutenant turned her imperious eyes in his direction, already resigned to the attentions of this shy young man. But before Ryan could speak, an immense explosion erupted from the street behind the TV station. The impact shook the ground and drummed against the pockmarked buildings. Fragments of masonry cascaded into the road as a cloud of smoke seethed into the sky, whipped upwards by the flames that rose from the detonation point somewhere to the southwest of the Christian enclave.

A sixfoot scimitar of plate glass fell from the window of the Holiday Inn, slicing through the football poster, and shattered around Gomez's feet. As he ran to the jeep, shouting at Ryan, there was a second explosion from the Fundamentalist sector of West Beirut. Signal flares were falling in clusters over the city, and the first rounds of gunfire competed with the whine of klaxons and the loudspeakers broadcasting a call to arms.

Ryan stumbled to his feet, brushing the dust from his combat jacket. Lieutenant Valentina had vanished into the strongpoint, where her men were already loading the machinegun in the barbette.

'Captain Gomez... The bomb? What set it off?'

'Treachery, Ryan the Royalists must have done a deal with the Nats.' He pulled Ryan into the jeep, cuffing him over the head. 'All this talk of peace. The oldest trap in the world, and we walked straight into it...'

More than treachery, however, had taken place. Armed militia men filled the streets, taking up their positions in the blockhouses and strongpoints. Everyone was shouting at once, voices drowned by the gunfire that came from all directions. Powerful bombs had been cunningly planted to cause maximum confusion, and the nervous younger soldiers were firing into the air to keep up their courage. Signal flares were falling over the city in calculated but mysterious patterns. Everywhere blue helmets and berets were lying discarded in the gutter.

When Ryan reached his aunt's apartment he found Dr Edwards and two UN guards waiting for him.

'Ryan, it's too late. I'm sorry.'

Ryan tried to step past to the staircase, but Dr Edwards held his arms. Looking up at this anxious and exhausted man, Ryan realised that apart from the UN observers he was probably the only one in Beirut still wearing the blue helmet.

'Dr Edwards, I have to look after Louisa and my aunt. They're upstairs.'

'No, Ryan. They're not here any longer. I'm afraid they've gone.'

'Where? My God, I told them to stay here!'

'They've been taken as hostages. There was a commando raid timed for the first explosion. Before we realised it, they were in and out.'

'Who?' Confused and frightened, Ryan stared wildly at the street, where armed men were forming into their platoons. 'Was it the Royalists, or the Nats?'

'We don't know. It's tragic, already there have been some foul atrocities. But they won't harm Louisa or your aunt. They know who you are.'

'They took them because of me...' Ryan lifted the helmet from his head. He stared at the blue bowl, which he had carefully polished, trying to make it the brightest in Beirut.

'What do you plan to do, Ryan?' Dr Edwards took the helmet from his hands, a stage prop no longer needed after the last curtain. 'It's your decision. If you want to go back to your unit, we'll understand.'

Behind Dr Edwards one of the observers held Ryan's rifle and webbing. The sight of the weapon and its steeltipped bullets brought back Ryan's old anger, that vague hatred that had kept them all going for so many years. He needed to go out into the streets, track down the kidnappers, revenge himself on those who had threatened his aunt and Louisa.

'Well, Ryan...' Dr Edwards was watching him in a curiously distant way, as if Ryan was a laboratory rat at a significant junction in a maze. 'Are you going to fight?'

'Yes, I'll fight...'Ryan placed the blue helmet firmly on his head. 'But not for war. I'll work for another ceasefire, doctor.'

It was then that he found himself facing the raised barrel of his own rifle. An expressionless Dr Edwards took his wrists, but it was some minutes before Ryan realised that he had been handcuffed and placed under arrest.

For an hour they drove southeast through the suburbs of Beirut, past the derelict factories and shantytowns, stopping at the UN checkpoints along the route. From his seat in the back of the armoured van, Ryan could see the ruined skyline of the city. Funnels of smoke leaned across the sky, but the sound of gunfire had faded. Once they stopped to stretch their legs, but Dr Edwards declined to talk to him. Ryan assumed that the physician suspected him of being involved with the conspirators who had broken the ceasefire. Perhaps Dr Edwards imagined that the whole notion of ceasefire had been a devious scheme in which Ryan had exploited his contacts among the young...?

They passed through the second of the perimeter fences that enclosed the city, and soon after approached the gates of a military camp built beside a deserted sanatorium. A line of olivegreen tents covered the spacious grounds. Arrays of radio antennae and television dishes rose from the roof of the sanatorium, all facing northwest towards Beirut.

The van stopped at the largest of the tents, which appeared to house a hospital for wounded guerrillas. But within the cool green interior there was no sign of patients. Instead they were walking through a substantial arsenal. Rows of trestle tables were loaded with carbines and machineguns, boxes of grenades and mortar bombs. A UN sergeant moved among this mountain of weaponry, marking items on a list like the owner of a gun store checking the day's orders.

Beyond the arsenal was an open area that resembled the newsroom of a television station. A busy staff of UN observers stood beneath a wall map of Beirut, moving dozens of coloured tapes and stars. These marked the latest positions in the battle for the city being screened on the TV monitors beside the map.

'You can leave us, corporal. I'll be in charge of him now.' Dr Edwards took the rifle and webbing from the UN guard, and beckoned Ryan into a canvaswalled office at the end of the tent. Plastic windows provided a clear view into an adjacent room, where two women clerks were rolling copies of a large poster through a printing press. The blownup photograph of a Republican atrocity, it showed a group of murdered women who had been executed in a basement garage.

Staring at this gruesome image, Ryan guessed why Dr Edwards still avoided his eyes.

'Dr Edwards, I didn't know about the bomb this morning, or the surprise attack. Believe me'

'I believe you, Ryan. Everything's fine, so try to relax.' He spoke curtly, as if addressing a difficult patient. He laid the rifle on his desk, and released the handcuffs from Ryan's wrists. 'You're out of Beirut for good now. As far as you're concerned, the ceasefire is permanent.'

'But... what about my aunt and sister?'

'They've come to no harm. In fact, at this very moment they're being held at the UN post near the Football Stadium.'

'Thank God. I don't know what went wrong. Everyone wanted the ceasefire...' Ryan turned from the atrocity posters spilling endlessly through the slim hands of the UN clerks. Pinned to the canvas wall behind Dr Edwards were scores of photographs of young men and women in their combat fatigues, caught unawares near the UN observation posts. In pride of place was a large photograph of Ryan himself. Assembled together, they resembled the inmates of a mental institution.

Two orderlies passed the doorway of the office, wheeling a trolley loaded with assault rifles.

'These weapons, doctor? Are they confiscated?'

'No as it happens, they're factorynew. They're on their way to the battlefield.'

'So there's more fighting going on outside Beirut...' This news was enough to make Ryan despair. 'The whole world's at war.'

'No, Ryan. The whole world is at peace. Except for Beirut that's where the weapons are going. They'll be smuggled into the city inside a cargo of oranges.'

'Why? That's mad, doctor! The militias will get them!'

'That's the point, Ryan. We want them to have the weapons. And we want them to keep on fighting.'

Ryan began to protest, but Dr Edwards showed him firmly to the chair beside the desk.

'Don't worry, Ryan, I'll explain it all to you. Tell me first, though have you ever heard of a disease called smallpox?'

'It was some sort of terrible fever. It doesn't exist any more.'

'That's true almost. Fifty years ago the World Health Organisation launched a huge campaign to eliminate smallpox, one of the worst diseases mankind has ever known, a real killer that destroyed tens of millions of lives. There was a global programme of vaccination, involving doctors and governments in every country. Together they finally wiped it from the face of the earth.'

'I'm glad, doctor if only we could do the same for war.'

'Well, in a real sense we have, Ryan almost. In the case of smallpox, people can now travel freely all over the world. The virus does survive in ancient graves and cemeteries, but if by some freak chance the disease appears again there are supplies of vaccine to protect people and stamp it out.'

Dr Edwards detached the magazine from Ryan's rifle and weighed it in his hands, showing an easy familiarity with the weapon that Ryan had never seen before. Aware of Ryan's surprise, he smiled wanly at the young man, like a headmaster still attached to a delinquent pupil.

'Left to itself, the smallpox virus is constantly mutating. We have to make sure that our supplies of vaccine are uptodate. So WHO was careful never to completely abolish the disease. It deliberately allowed smallpox to flourish in a remote corner of a thirdworld country, so that it could keep an eye on how the virus was evolving. Sadly, a few people went on dying, and are still dying to this day. But it's worth it for the rest of the world. That way we'll always be ready if there's an outbreak of the disease.'

Ryan stared through the plastic windows at the wall map of Beirut and the TV monitors with their scenes of smoke and gunfire. The Hilton was burning again.

'And Beirut, doctor? Here you're keeping an eye on another virus?'

'That's right, Ryan. The virus of war. Or, if you like, the martial spirit. Not a physical virus, but a psychological one even more dangerous than smallpox. The world is at peace, Ryan. There hasn't been a war anywhere for thirty years there are no armies or air forces, and all disputes are settled by negotiation and compromise, as they should be. No one would dream of going to war, any more than a sane mother would shoot her own children if she was cross with them. But we have to protect ourselves against the possibility of a mad strain emerging, against the chance that another Hitler or Pol Pot might appear.'

'And you can do all that here?' Ryan scoffed. 'In Beirut?'

'We think so. We have to see what makes people fight, what makes them hate each other enough to want to kill. We need to know how we can manipulate their emotions, how we can twist the news and trigger off their aggressive drives, how we can play on their religious feelings or political ideals. We even need to know how strong the desire for peace is.'

'Strong enough. It can be strong, doctor.'

'In your case, yes. You defeated us, Ryan. That's why we've pulled you out.' Dr Edwards spoke without regret, as if he envied Ryan his dogged dream. 'It's a credit to you, but the experiment must go on, so that we can understand this terrifying virus.'

'And the bombs this morning? The surprise attack?'

'We set off the bombs, though we were careful that no one was hurt. We supply all the weapons, and always have. We print up the propaganda material, we fake the atrocity photographs, so that the rival groups betray each other and change sides. It sounds like a grim version of musical chairs, and in a way it is.'

'But all these years, doctor...' Ryan was thinking of his old comradesinarms who had died beside him in the dusty rubble. Some had given their lives to help wounded friends. 'Angel and Moshe, Aziz... hundreds of people dying!'

'Just as hundreds are still dying of smallpox. But thousands of millions are living in peace. It's worth it, Ryan; we've learned so much since the UN rebuilt Beirut thirty years ago.'

'They planned it all the Hilton, the TV station, the McDonald's...?'

'Everything, even the McDonald's. The UN architects designed it as a typical world city a Hilton, a Holiday Inn, a sports stadium, shopping malls. They brought in orphaned teenagers from all over the world, from every race and nationality. To begin with we had to prime the pump the NCOs and officers were all UN observers fighting in disguise. But once the engine began to turn, it ran with very little help.'

'Just a few atrocity photographs...' Ryan stood up and began to put on his webbing. Whatever he thought of Dr Edwards, the reality of the civil war remained, the only logic that he recognised. 'Doctor, I have to go back to Beirut.'

'It's too late, Ryan. If we let you return, you'd endanger the whole experiment.'

'No one will believe me, doctor. Anyway, I must find my sister and Aunt Vera.'

'She isn't your sister, Ryan. Not your real sister. And Vera isn't your real aunt. They don't know, of course. They think you're all from the same family. Louisa was the daughter of two French explorers from Marseilles who died in Antarctica. Vera was a foundling brought up by nuns in Montevideo.'

'And what about...?'

'You, Ryan? Your parents lived in Halifax, Nova Scotia. You were three months old when they were killed in a car crash. Sadly, there are some deaths we can't yet stop..

Dr Edwards was frowning at the wall map of Beirut visible through the plastic window. A signals sergeant worked frantically at the huge display, pinning on clusters of incident flags. Everyone had gathered around the monitor screens. An officer waved urgently to Dr Edwards, who stood up and left the office. Ryan stared at his hands while the two men conferred, and he scarcely heard the physician when he returned and searched for his helmet and sidearm.

'They've shot down the spotter plane. I'll have to leave you, Ryan the fighting's getting out of control. The Royalists have overrun the Football Stadium and taken the UN post.'

'The Stadium?' Ryan was on his feet, his rifle the only security he had known since leaving the city. 'My sister and aunt are there! I'll come with you, doctor.'

'Ryan... everything's starting to fall apart; we may have lit one fuse too many. Some of the militia units are shooting openly at the UN observers.' Dr Edwards stopped Ryan at the door. 'I know you're concerned for them, you've lived with them all your life. But they're not'

Ryan pushed him away. 'Doctor, they are my aunt and sister.'

It was three hours later when they reached the Football Stadium. As the convoy of UN vehicles edged its way into the city, Ryan gazed at the pall of smoke that covered the ruined skyline. The dark mantle extended far out to sea, lit by the flashes of high explosives as rival demolition squads moved through the streets. He sat behind Dr Edwards in the second of the armoured vans, but they could scarcely hear themselves talk above the sounds of rocket and machinegun fire.

By this stage Ryan knew that he and Dr Edwards had little to say to each other. Ryan was thinking only of the hostages in the overrun UN post. His discovery that the civil war in Beirut was an elaborate experiment belonged to a numb area outside his mind, an emotional black hole from which no light or meaning could escape.

At last they stopped near the UN post at the harbour in East Beirut. Dr Edwards sprinted to the radio shack, and Ryan unstrapped his blue helmet. In a sense he shared the blame for this uncontrolled explosion of violence. The rats in the war laboratory had been happy pulling a familiar set of levers the triggers of their rifles and mortars and being fed their daily pellets of hate. Ryan's dazed dream of peace, like an untested narcotic, had disoriented them and laid them open to a frenzy of hyperactive rage...

Ryan, good news!' Dr Edwards hammered on the windscreen, ordering the driver to move on. 'Christian commandos have retaken the Stadium!'

'And my sister? And Aunt Vera?'

'I don't know. Hope for the best. At least the UN is back in action. With luck, everything will return to normal.'

Later, as he stood in the sombre storeroom below the concrete grandstand, Ryan reflected on the ominous word that Dr Edwards had used. Normal...? The lights of the photographers' flashes illuminated the bodies of the twenty hostages laid against the rear wall. Louisa and Aunt Vera rested between two UN observers, all executed by the Royalists before their retreat. The stepped concrete roof was splashed with blood, as if an invisible audience watching the destruction of the city from the comfort of the grandstand had begun to bleed into its seats. Yes, Ryan vowed, the world would bleed The photographers withdrew, leaving Ryan alone with Louisa and his aunt. Soon their images would be scattered across the ruined streets, pasted to the blockhouse walls.

'Ryan, we ought to leave before there's a counterattack.' Dr Edwards stepped through the pale light. 'I'm sorry about them whatever else, they were your sister and aunt.'

'Yes, they were..

'And at least they helped to prove something. We need to see how far human beings can be pushed.' Dr Edwards gestured helplessly at the bodies. 'Sadly, all the way.'

Ryan took off his blue helmet and placed it at his feet. He snapped back the rifle bolt and drove a steeltipped round into the breech. He was only sorry that Dr Edwards would lie beside Louisa and his aunt. Outside there was a momentary lull in the fighting, but it would resume. Within a few months he would unite the militias into a single force. Already Ryan was thinking of the world beyond Beirut, of that far larger laboratory waiting to be tested, with its millions of docile specimens unprepared for the most virulent virus of them all.

'Not all the way, doctor.' He levelled the rifle at the physician's head. 'All the way is the whole human race.'

1989.

Dream Cargoes Across the lagoon an eager new life was forming, drawing its spectrum of colours from a palette more vivid than the sun's. Soon after dawn, when Johnson woke in Captain Galloway's cabin behind the bridge of the Prospero, he watched the lurid hues, cyanic blues and crimsons, playing against the ceiling above his bunk. Reflected in the metallic surface of the lagoon, the tropical foliage seemed to concentrate the Caribbean sunlight, painting on the warm air a screen of electric tones that Johnson had only seen on the nightclub faades of Miami and Vera Cruz.

He stepped onto the tilting bridge of the stranded freighter, aware that the island's vegetation had again surged forward during the night, as if it had miraculously found a means of converting darkness into these brilliant leaves and blossoms. Shielding his eyes from the glare, he searched the 600 yards of empty beach that encircled the Prospero, disappointed that there was no sign of Dr Chambers' rubber infaltable. For the past three mornings, when he woke after an uneasy night, he had seen the craft beached by the inlet of the lagoon. Shaking off the overlit dreams that rose from the contaminated waters, he would gulp down a cup of cold coffee, jump from the stern rail and set off between the pools of leaking chemicals in search of the American biologist.

It pleased Johnson that she was so openly impressed by this once barren island, a leftover of nature seven miles from the northeast coast of Puerto Rico. In his modest way he knew that he was responsible for the transformation of the nondescript atoll, scarcely more than a forgotten garbage dump left behind by the American army after World War II. No one, in Johnson's short life, had ever been impressed by him, and the biologist's silent wonder gave him the first sense of achievement he had ever known.