Macy drove out across the dark plain, past fields of vacuum organisms, past a low range of hills where every New Year people from habitats and oases round and about used explosive charges and drills and chisels to sculpt from the rock-hard ice fantastically detailed statues and frescos of real and imaginary animals, castles, temples, palaces and fantasy landscapes, some in the natural, sombre colours of the ice, others frosted white or sprayed with coloured water. The road swung around the far edge of this gigantic fantasia and ran in a straight line north-east towards the network of ridges and scarps associated with Carthage Linea's gigantic trough. Saturn's crescent slowly climbed beyond the horizon. The road cut through a series of ridges softened by a mantling of dust created by several billion years of micrometeorite impacts, and Macy swung away from it and drove north, driving up a long slope that gave out at an abrupt scarp that dropped to a dished plain where a scattering of oases and shelters glittered in vivid shades of green like exquisitely detailed pieces of jewellery.

Macy thought of a smart rock hurtling out of the black sky: as long as it was travelling fast enough, it didn't have to be very big, striking one of those little tents and vaporising it, punching a fresh crater in the landscape. She imagined rocks targeted at every settlement, dozens of rocks smashing down on Dione, pounding it hour after hour . . .

She followed a narrow road that switchbacked down the scarp, drove out across the plain towards the new oasis. A crew of construction robots had just completed the tent and its infrastructure, and the Jones-Truex-Bakaleinikoff clan had won the contract to quicken it. Elephant was parked on the far side, its shocking pink hull vivid against the tan and umber landscape. Macy pulled up next to the tent's service lock, fastened her helmet and climbed outside, and started to haul insulated boxes and drums onto a sledge. She hadn't been working long when Newt came around the flank of the tent, loping along eagerly. The chest-plate of his white pressure suit was decorated with the dark-blue sky and blowsy suns of Van Gogh's Starry Night.

'I'm sorry I'm late,' Macy said. 'Something came up.'

'You could have called.'

'I knew you'd wait. And I'm not that late.'

'Can't you unload this stuff when we get back? You're going to make us even later.'

'I don't want to leave them in the rolligon. If its battery gives out, the cold will get to them.'

'The battery won't give out.'

'If you give me a hand, it'll take half as long.'

Newt helped her load the rest of the rolligon's cargo onto the sledge and they pulled it into the big airlock and cycled through. The space under the slanting sides of the tent was divided into two by a sinuous ridge decorated here and there with faceted outcrops of black basalt and covered in a layer of artificial topsoil derived from particles of smectite clays and siderite that had been ground to glassy sand and conditioned in a bioreactor. A gardening robot had laid it down a few days ago. After checking the viability of its microflora and biota and making any adjustments she felt necessary, Macy was going to seed every square centimetre with a mix of fast-growing grasses and clovers. She would return two weeks later to plough in the catch crop to provide green manure, and leave the soil ready for the mature plant cover.

She shucked her helmet and told Newt to sit down, she had something to tell him.

'Are you backing out?' he said, after he'd taken off his helmet and perched on the edge of the sledge.

'I still want to go. But you should know that your mother knows about us.'

'She knows what you're planning to do?'

'Maybe. I don't know. She didn't ask me about it, and I didn't ask her. But she made it plain that she knew you were helping me.'

After Macy had given Newt a summary of the conversation, he said, 'It was Yuldez, wasn't it?'

'Who told Marisa Bassi? I think so.'

'He asked me for a ride last night. Turned up as I was getting ready to leave, said I could drop him off at Paris on my way to pick up the cargo. I told him it was too far out of my way, he could get the train. I guess that's what he did.'

'And early the next morning Marisa Bassi calls your mother. It fits.'

'Let me deal with him.'

'Your mother said she'd take care of him. Besides, it isn't as if he gave away any real secret. Everyone in the clan knows how I voted.'

'He wanted to get you into trouble.'

'Marisa Bassi would have gone after me anyway, when he realised I wasn't going to cooperate.'

'This plan of yours had better work, then. Are you going to tell me exactly who it is you're planning to meet?'

'You'll see soon enough. When we get to Enceladus.'

6.

Euclides Peixoto called Sri a few hours before she was due to appear before the Senate Intelligence Committee. She was taking breakfast with Alder and a clutch of aides, lawyers and councillors, rehearsing her testimony. After she walked out onto the terrace, Euclides told her that the meeting with the traitor, Lieutenant Colonel Manuel Montagne, would take place at three o'clock in the afternoon.

'This afternoon?'

'Don't worry, Professor Doctor. You have plenty of time,' Euclides said, and told her that she was to walk west along the central promenade by the Lago Paranoa. The traitor would be waiting for her at the far end.

'And then?'

'And then it will proceed as arranged. He has no reason to suspect you, and my men will of course be watching. In the unlikely event that there is trouble, they will intervene at once. But I am sure that you will do your best to make sure that there is no trouble, yes?'

'Don't gloat. It demeans both of us.'

'You're in no position to take a moral tone with me. After you collect the data needle, you will meet with one of my aides. You will exchange the needle for one with the salted data, and that's what you will take to my uncle.'

'That's all I have to do,' Sri said, although she knew that it wasn't. She had plans of her own now.

'That's all. You made the right decision, Professor Doctor. You won't regret helping us.'

At the Senate Intelligence Committee, Sri read out her answers to questions that had been given to her in advance, and after a little light cross-examination the chairman thanked her for her help and told her that she was discharged. Then it was Alder's turn to give his sworn deposition; sitting beside him. Sri was proud of how fearless he seemed as he stood before the four senators and their advisers and recited his answers in a clear and calm voice.

Afterwards, bodyguards drove Alder back to the apartment, and Yamil Cho drove Sri across the city to the rendezvous with Colonel Montagne. Through a dense traffic of bicycles and bicycle carts towing improbably large loads, army and civilian trucks, buses and jitneys so crowded that they looked like heaps of people locked together like army ants around a morsel of food. Past monolithic superquadras that blotted out much of the sky and cast the tree-lined avenues in perpetual shadow. Apartments and shops were crammed into the broad terraces of their lower floors and tiers of farm platforms rose high above, clad in racks of solar panels and topped by windmill generators whose giant blades heliographed shards and splinters of sunlight.

Sri loathed Brasilia. She loathed the brutalist architecture. She loathed the heat and the bone-dry air and the dust that blew from the planalto and turned the sky blood red. Most of all, she loathed the crush of people on the streets, the proles with their cheap garish clothes and unreconstructed and imperfect bodies and faces, sheer overwhelming numbers of them, far too many people crushed together out of necessity and ideology. The land was for Gaia; the cities for people. It was the culmination of a trend that had begun with the invention of agriculture. Now almost everyone on Earth lived in a city, and the cities no longer sucked the life out of the surrounding countryside, no longer drew on water and food and mineral resources for a hundred or a thousand miles around, but were self-contained, recycling water and garbage, growing food in farm towers and on rooftops and elevated platforms. Urban islands isolated like pockets of plague from the regenerated and reconstructed wildernesses that surrounded them.

The stink of the street infiltrated the limousine's air-conditioning and clung greasily to Sri's skin. Sweat and cheap perfume, incense from altars and shrines, the smoke of the cooking fires of street vendors, the sweet tang of burnt gasohol. Music in a dozen clashing styles thumped from sound systems that adorned the vehicles all around, from loudspeakers above shops and the stalls along the sidewalks under the huge trees that lined the avenues. People lived their lives right out in the open, like animals. All along the broad sidewalks they were having their hair cut or their teeth fixed, being tattooed or scanned, eating, watching puppet shows or acrobats or dancers, listening to itinerant preachers ranting at street corners, praying at roadside shrines dedicated to a zoo of totemic spirit animals. To the proles, Gaia was not a scientific concept, the intermeshed totality of the Earth's biomes, but an ancient goddess, powerful yet vulnerable. Through their chosen spirit animal they prayed to Her for intercession in their lives, prayed for forgiveness of the great wounds that humankind had caused, and prayed for Her renewal. In their rude shrines, She was depicted as Aphrodite rising naked from the sea on a scallop shell, or a many-armed dancer, or a maternal figure vast and fertile, or a laughing child dancing through a sun-spangled forest.

An amazing chasm of ignorance, no way of filling it, Sri thought as she stared at the carnival streets through the smoked glass of the armoured limousine. Sometimes she dreamed of plagues that would winnow humanity to a sustainable level. Of a green, wild planet in which just ten million people roamed the plains and forests, sailed the clean blue oceans. Tall strong intelligent people who lived lightly on the land, linked by a planetary net, carrying civilisation in their heads. A Utopia in which everyone was like her. Billions had been killed by climate change and the wars for water and agricultural land, and billions more had died during the Overturn, but it had not been enough.

The frigid empty landscapes of the moons of Saturn rose in her mind's eye. The gardens of the cities and oases. Green cathedrals celebrating the triumph of rationality.

She became aware that the traffic was slowing, bunching up. Arpeggios of horns. The shouts of frustrated drivers. The animal roar of a crowd packed into a plaza, spilling into the road. Yamil Cho used his headset to talk with someone, then told Sri that there was a small problem, but it should be negotiable.

'Is it some kind of meeting?'

'I believe it's a war riot, ma'am.'

'A riot?'

'People get stirred up by propaganda and eventually their anger finds an outlet. They burn effigies, chant slogans. Usually nothing serious. The news channels cover them like they cover futsal matches.'

'I don't watch the news channels.'

Sri remembered something that Oscar had told her long ago, when she had complained one day about the sheer numbers of people who contributed nothing to the world, who were no more than fleshy vessels for the blind reproductive urges of their genes. According to him, mob behaviour had evolved soon after human beings had first crowded together in cities. Mobs were ugly and vicious but they were also purposeful, congregating around a wound in the populace's psyche like white blood cells around an infection in the body. They were safety valves for frustration and dissatisfaction; they united a population against a real or imagined enemy. Mobs have always been with us, Oscar had said. Every kind of government had been tried, but the mob was a constant of civilisation. Rulers believed that they were in control, that they had been elevated above the herd and governed by common consent or brute force or divine right, but in reality they were merely servants of the mob.

Yamil Cho talked into his headset, then told Sri, 'The police assure us that we will be quite safe as long as we stay in our vehicle. I will get us out of here as soon as possible, but it is best to behave inconspicuously.'

'We are inside a limousine, Mr Cho. We are hardly inconspicuous. And besides, we must not miss the rendezvous. Get us away from here right now.'

'I will do my best,' Yamil Cho said, and began to edge the limousine forward.

The crowd surged around a giant people tree in the centre of the plaza. People trees were a legacy of Avernus, cut by her before she had left Earth for the Moon, before the Overturn. They were planted in every city. Their abundant sugar-rich sap could be tapped to make syrup or wine or beer and their seed pods could be crushed to make biofuel; they produced protein-rich nodules at the junctions of their branches, their bark yielded several spices and an antibiotic, or could be boiled to make a kind of paper cloth, and their nutritious leaves could be eaten raw. People could live out their entire lives in them and never want for anything. Many holy men and women did just that; it was a rare tree that was not inhabited by a mendicant or a seeress.

This one had something hanging from the very end of one of its broad lower branches. As the limousine crept past the outer fringe of the crowd, Sri saw that it was the corpse of an albino man, head flopping broken-necked against his shoulder, clothes tattered, a placard fastened to his chest with two words lettered in what looked like blood. Against Nature. People were beating at the corpse's feet and legs with sticks as if it were a pinata. They were pelting it with stones and fruit. Even shoes. They were pulling off their shoes and throwing them at the corpse.

Had they mistaken him for an Outer, or was he a surrogate for their inchoate rage against the posthumans? Sri realised that it didn't matter. What mattered was the mob's fury.

A small flock of police drones and one-man copters hung at different levels above the stepped terraces and setbacks of the superquadra that surrounded the plaza on three sides. Yamil Cho explained that the police usually didn't intervene directly in situations like this because it generally inflamed the mob.

'They are pumping pheromones to make the rioters more peaceable.'

'It doesn't seem to be working,' Sri said.

More and more people were crowding into the plaza, like ants swarming a sugar lure. People tried to stare through the limo's mirrored windows, a parade of leering, confused, angry, tearful faces. Fists battered the limo's body, drummed on its roof like rain. It rocked on its sturdy suspension like a small boat in a choppy sea. Out across the crowd, small knots of fighting were beginning to break out as the mob turned its rage on itself. Something thumped on the window a few centimetres from Sri's face; pieces of fruit slid down the glass, leaving a slimy trail. And suddenly the limousine was the centre of a barrage of fruit and stones. A man battered at the windshield with a stake torn from a roadside stall. Yamil Cho aimed a grazer at him and the man dropped the stake and fell to his knees shrieking in agony as the weapon's beam triggered his pain receptors. Others surged forward and started to rock the limousine from side to side, and were thrown back when fifty thousand volts surged through the limousine's body.

Yamil Cho advised Sri to buckle her safety harness. As she clipped herself in place, the limousine pulled out around a truck painted with pious slogans and mounted the sidewalk, scattering pedestrians and smashing through stalls as it picked up speed. Yamil Cho talked calmly to the police as he aimed the limousine with pinpoint precision. As it slewed back onto the road, a copter beat down overhead, lights flashing and siren wailing, and other vehicles began to clear out of the way.

A few blocks later, they were driving through normal traffic, past a normal street scene. Yamil Cho thanked the copter and it stood on its nose and sheered away, heading back towards the riot.

'Are they common, these war riots?' Sri said.

'There's at least one a day now, ma'am. And not just in Brasilia, either.'

'It can't be stopped,' Sri said.

'They generally burn themselves out pretty quickly,' Yamil Cho said.

'I mean the war can't be stopped, Mr Cho. The people have spoken. They want it.'

'Yes, ma'am.' Yamil Cho drove for a block, then said, 'If I may be so bold, I think you're doing the right thing. Not because war is inevitable, but because it's the right thing to do.'

'Thank you, Mr Cho,' Sri said, surprised and touched. She had never before heard the man express an opinion.

The place where she was supposed to meet with Lieutenant Colonel Montagne was in the broad park of grass and clumps of trees that ran beside the long lake which centuries ago had been created by diverting three rivers. Sailboats were out on the water, colourful as a flock of butterflies, tacking back and forth in the hot breeze. Sri walked along the central promenade past stalls and benches and clumps of picnic tables. Families. Sweethearts strolling arm in arm. Children sitting rapt before a puppet show.

No one was waiting for her at the far end of the promenade, but a scrap of paper had been screwed into the mesh seat of the very last bench. A street address was written on it.

'It's a good precaution,' Yamil Cho said, when Sri returned to the limousine, hot and out of temper. 'This fellow knows what he is doing.'

'Playing silly games won't help him.'

'Of course not.'

'Are we still being followed?'

'We lost the first team when we went past the war riot, but another team was waiting for us right here. I can lose them easily enough along the way. Just say the word.'

Sri shook her head. 'I want them to follow us. I want Euclides Peixoto to know that I did exactly as he asked.'

The new rendezvous was a street-corner lanchonete near the Cemiterio da Esperanca, no different from a thousand such. Tables and chairs scattered under the broad shady branches of a people tree, a stall that sold coffee and fruit juice, fried doughnuts and empadinhas. Sri took a seat and when the waiter came over ordered a glass of mango juice that she had no intention of drinking - the stuff would be a gross cocktail of bacteria and impurities. After a couple of minutes a young black-haired man who was not the waiter brought the glass to her table and set it down on a paper napkin.

'I am a friend of Colonel Montagne,' he said. 'Do you know that you are being watched?'

'I suspected it,' Sri said.

'What you need is in the fold of the napkin. You understand why we must take precautions. It is not for our safety, but for yours.'

For a moment, Sri felt the urge to tell him that this was a charade, that Euclides Peixoto was planning to salt the information, and in any case the green saint they no doubt revered didn't need it, this was just his way of testing her loyalty. This young man and Colonel Montagne probably believed that they were changing history, but they were caught up in a game they didn't understand, out-thought and outmaneuvered, doomed. She could save their lives with just a few words. The impulse rose up in her like a sickness, making her dizzy and lightheaded, and then it was gone. She was in control of herself again.

'I want to say that it is a marvellous thing to meet you, Dr Hong-Owen,'

the young man said, with a sudden bright smile. 'You are doing great and important work. I can't express my admiration for your bravery in coming here, and for standing in front of that committee of old fools and telling them the truth about our brothers and sisters.'

'Brothers . . . ?'

'We are all of us children of Gaia. Here on Earth, and on all the other worlds. This war the old men want - you and I know it is quite artificial. They want to deny evolution. They have remade the world for their own benefit and they are frightened of change because they know that change will unthrone them. I have read your work, Dr Hong-Owen. That you are on our side - it makes me happier than I can say. I know that you will ensure our little gift reaches the right person,' the young man said, and turned and walked away through the tables and chairs into the swirling crowds moving along the broad sidewalk.

A bumblebee-sized drone sped after him, flashing in the sunlight for a moment as it flew out of the shade of the tree, above the heads of the crowd. Sri carefully folded the paper napkin, slipped it into her pocket, and walked back to the limousine.

When Sri returned to the apartment, she found her sons playing a kind of water polo in the pool out on the big terrace. She stood in the shadows by the French windows, watching them splash and shout. Alder was quick and cunning, but Berry, graceful and strong in the water, had control of the ball for most of the time. Unlike Alder, he'd been conceived by natural means after Sri had seduced Stamount Home, a one-eighth-consanguineous member of the Peixoto family who at that time had been second-in-command of the security service.

Truthfully, Stamount had allowed himself to be seduced. He had almost been Sri's match in intelligence, cunning, and ambition. They would have founded a fine and powerful dynasty, but five months after Sri had allowed herself to conceive Stamount had been killed during a campaign to clear out a troublesome tribe of bandits that had been sabotaging the trans-Andean railway. Sri would always mourn him. She wore on the third finger of her left hand an intricate latticework ring of bone grown from a culture of his osteoblasts, and in honour of his memory had never once cut Berry, who had inherited his father's good looks but little else.

Berry was a cheerful child as long as he was given what he wanted as soon as he asked for it, but his intelligence was no more than average, he was lazy, and lately he had been exhibiting a streak of careless cruelty; after a couple of unfortunate incidents with his playmates, fortunately the children of servants, Sri had decided that he could not be trusted to be left alone with any child smaller than himself. Yet he was always deeply and unconditionally affectionate and loyal to his mother and to his brother, and Sri loved him in turn and was more patient and tolerant with him than with anyone else, knowing that he would always be dependent on her, would always need to be protected from the consequences of his foolish and impulsive nature. He left the pool when she called to him and dutifully trotted over and told her about his visit to one of the city's farms. She let his happy babble wash over her, allowed herself to relax. She was committed now. No turning back, no need to anguish over it.

But later, in bed, with Yamil Cho moving over her, as smoothly muscled as a snake, his skilful tongue and lips and fingers forcing her to bite her lips to keep from crying out, a face flashed in the hot dark behind her eyelids: the doomed young man who had delivered the data needle.

7.