There were a few nights in Dunwich, where the owner of the B&B kept telling her guests they were lucky to have found a room. Walking Dunwich Beach, showing his daughter wintering geese through binoculars so heavy they made her laugh, the man was glad they were not in Southwold or Walberswick. They were not so hemmed in by visitors. Each evening they had fish and chips or pub grub. Each night after she had gone to bed he hacked into next door's wifi to check his messages and monitor the forums.

On Thursday night he woke her. It was not long after midnight.

'Come on lovey,' he said. 'Keep it down. Let's not get anyone else up.'

'I hate you,' she said into her pillow.

'I know,' he said. 'Come on. Don't bring your phone.'

There was not much on the roads. Still, Dughan took them roundabout ways, through Blythborough, on the A145 towards Uggeshall, past still diggers where roads were being widened.

'Where are we going?' the girl asked, only once. She hunkered; she wouldn't ask him to turn up the heating.

Wrentham was on the western rim of the security zone. It went north along the A12, south on the B1127 to Southwold. Within it, in daylight, fields were still worked, for animal feed, and roads mostly open, but those were, legally, indulgences not rights; the area was, in the absence of an official escort, no-go after dark. Exceptional laws applied in that little triangle, the coast a 6-mile hypotenuse, its midpoint Covehithe.

Dughan stopped by a pub garden south of Wrentham. He opened the door for his daughter with his finger to his lips.

'Dad,' she said.

'Hush,' he said.

It was overcast and windy, shadows taking them and releasing them as Dughan found a way through undergrowth to the boundary ditch. They were both quiet as they crossed it. Holding their breath. Beyond, they walked eastward on the edges of the fields. 'Dad, seriously, you're crazy.' He had a torch but did not turn it on. When the moon came out enough he stopped and took bearings.

'They've got guns,' she said.

'That's why shhh.'

'What'll they do if they catch us?'

'Feed us to wolves.'

'Har har.'

They went still at the sound of a helicopter. The beam passed by half a field ahead, so bright it looked solid.

The air smelt. They could hear echoes. Dughan avoided the hamlet where until recently locals had lived, which had been requisitioned, with only minor scandal. They could see lit windows. They came instead at Covehithe from the north.

He stopped her by the roofless ruin of the church, pointed, heard her gasp. She stared while moonlight got past the clouds to the holed and broken walls, onto a low newer church inside the nave of the old. He smiled. When eventually she was done looking they continued through the graveyard. There was nothing at all frightening about the graves.

This close to the waves the land felt, as the girl said, misbehavicious. A good word to make her feel better. In the leafless trees of this region were cold, random and silent flares of light. Touch the soil, as Dughan did, and as his daughter did too at the sight of him, and it felt greasy, heavy, as if someone had poured cream onto loam.

'Which way are we going?'

'Careful lovey,' he said. 'The ground here...'

'How do you know it's tonight?'

For a while he didn't answer. 'Oh,' he said. 'Bits and pieces.' He looked over his shoulder the way they had come. 'Ways and means.'

'What if they find out?' She pointed at the cottages. She rolled her eyes when he said nothing.

They continued on the road past a sign forbidding exactly this last short walk, on tarmac so old it was becoming landscape. Perspective was peculiar. The smell should have been sappy and muddy and of the sea.

'Look!' His daughter gasped. The road stopped abruptly, rag-edged, fell into nothing. He watched her inch forward. 'It goes right off the cliff!'

'The sea's taking it all back,' he said. 'There used to be a lot more coast here. Careful.' But she had lain responsibly on her stomach at a certain proximity and put only her fingertips and eyes over the tarmac rim to look down its sheer crumble at the beach.

'Is it still going?' she said. Her voice was faint, she was dipping her mouth below road-level. 'Being eaten?' Dughan shrugged. Waited till she scootched back and turned to him, shrugged again.

He told her they would know within two or three hours if anything was going to happen. He did not say it was only hints and whispers he had to go on, trawlings from bulletin boards. Two names he knew, erstwhile colleagues, both announcing they'd be near Ipswich next week and did any of the old crew want a drink? The latest codes were beyond him, but that query and the night's sudden burst of encrypted chatter had been reasons enough to move.

So, he said, checked his watch and sat with her at the decomposing road-end. He was cross-legged, she with her chin on her knees, hugging them. She kept looking into the sea. The noise of it lulled them as if it were designed to. There was no light but the moon and those occasional sourceless mineral glows. Somewhere some insane bird, not a nightingale, was singing.

All their layers could not keep them warm. They were shaking hard when, after less than an hour, Dughan saw movement on the beach. He motioned for his daughter to stay still and looked through his binoculars at lights jouncing on the shingle. Three sets of headlamps stopped, overlaying each other, illuminating the sea and a strip of the shore.

'It's them,' he said. 'They're setting up. They must've...' The girl could tell his excitement was not wholly enthusiasm. 'They've... we're on.'

He could make out nothing beyond the headlight gaze, and hear nothing but waves. He recced once more but they were not observed. This cliff-top was out of bounds and they, intruders, were alone. His daughter kept watching the water. Dughan wondered if she would complain or ask how long or anything, but she did not. Twenty minutes later, it was she who pointed, who first saw something in the sea.

There were no helicopters now. Nothing so noisy. No downcast beams to light up what was coming, breaking water, way off the coast. It was only moonlit. A tower. A steeple of girders. Streaming, and rising.

The girl stood. The metal was twisted. Off-true and angular like a skew-whiff crane, resisting collapse. It did not come steadily but lurched, hauling up and landward in huge jerks. After each a swaying hesitation; then another move higher, and closer.

The lights on the beach went out. Flame ignited at the tower's tip. Sooty sepia guttering lit the shaft. The sea at its base spread flat and fell away from suddenly rising intricate blockness, black, angled and extrusioned. As if a quarried wedge of the seabed itself had come up to look.

The towerwork was on a platform. In the glow of the thing's own flame they saw edificial flanks, the concrete and rust of them, the iron of the pylon barnacled, shaggy with benthic growth now lank gelatinous bunting.

It was coming at the Covehithe cliff. Under its stains and excrescences were more regular markings, stencilled warnings. Paint remnants: an encircled H.

Another step – because these were clumsy steps with which it came – and all the main mass was out of the water and raining brine. It waded. Each concrete cylinder leg a building or a smokestack wide. The two on one side came forward together, then those on the other. Pipes dangled from its roof-high underside, clots of it fell back into the sea. It wore steel containers, ruins of housing like a bad neighbourhood, old hoists, lift shafts emptying of black water.

A few waves-width from the beach, it hesitated. It licked the air with a house-sized flame.

'P-36,' the man said. 'Petrobras.'

One of the cars below turned its headlamps back on. The rig shied. Dughan hissed. But the lights quickly dipped and after a moment he said, 'It's probably ok now.'

The platform was at the level of their cliff-top. Now the girl understood its strange ungainliness. On each side, its supports merged at their base, into two horizontal struts, so it moved like a quadruped skiing. What must have been ten feet of water lapped at the struts like a puddle at a child's shoes. The rig facelessly faced north and slide-stamped along the shoreline.

'Quick,' the man said. They took the cliff-edge path, a hedge to their right, the oil platform's tower lurching beside them above its leaves.

'Went down 2001,' Dughan said. 'Roncador field.'

'How many people died?'

'When it sank? No one.'

'Have you... is this the first...?'

He took a moment to stop, to turn and meet her eye. They could hear the flame bursts now. Its straining metal. 'I've never seen it before, lovey' he said.

The path descended. She had been too small when her father left to imagine stories of his exploits, to be proud or afraid. All she remembered were his returnings, an exhausted, careful man who lifted her on to his lap and kissed her with wary love, brought her toys and foreign sweets. When later she had asked him what he had done on those trips, his answers were so vague guilt had hushed her. She did not ask about his injuries.

The rig was slowing. The smell was stronger and the ground, the air juddered, not only in time to its huge steps. Dughan stopped at the last path-end trees. He and his daughter hugged the trunks and watched the oil rig sway in their direction. He held her hand. The girl watched him, too, but he showed no signs of angst, no flashback, no fear.

* * *

On an autumn evening in the earlyish years of the 21st Century, a fishing boat south-east of Halifax radioed an SOS, under attack – the transmission was unclear. Rescuers found two traumatised survivors in a wash of scattered debris. As they did, the cause of the catastrophe reached the coast. Authorities could not suppress civilian footage of what had come back.

It was the Rowan Gorilla I. That was the first. No Piper Alpha, no Deepwater Horizon; an undistinguished disaster. A tripod jack-up rig lost to storms and hull-fracture in 1988, on its way to the North Sea. Scattered surely by its capsizing and by 30 years below but there, back. Cramped-looking for all its enormity, latticed legs braced halfway through its platform, jutting above it and below into the sea. In the videos the three skyward leg-halves switch and lean creaking towards each other, sway away again like cranes triple-knitting, as it walks the muck on spudcap feet. It staggered like a crippled Martian out of the water and onto Canada.

It shook the coast with its steps. It walked through buildings, swatted trucks then tanks out of its way with ripped cables and pipes that flailed in inefficient deadly motion, like ill-trained snakes, like too-heavy feeding tentacles. It reached with corroded chains, wrenched obstacles from the earth. It dripped seawater, chemicals of industrial ruin and long-hoarded oil.

Ten miles inland, a line of artillery blew the thing apart. Later they made that area a memorial park. Sections of the rig's deck they left unsalvaged, preserved amid flowerbeds.

By panics and fuckups, Dughan's unit had been trapped on the far side of the wounded platform, between the Rowan Gorilla I, they later realised, and the sea. A third of his comrades had been killed. Crushed, torn by wires, caught in its final explosion, bequeathing him years of dreams and memories of trodden men.

The world was still reeling, investigation barely begun, when the Ocean Express, capsized in 1976 with 13 dead, which must have been quietly recomposing itself at the bottom of the Gulf of Mexico, stood upright in relatively shallow water and strode landward.

Fighter jets scrambled from Eglin inflicted severe damage, slowed it, and the USS Carney torpedoed one of its supports. The rig buckled, tilted and seemed to wait kneeling like a bettered knight. The Carney had shelled it apart.

Dughan saw this from the Carney's deck. He and several comrades had been flown in as advisors to the US navy. He was combatant himself again soon enough, at the return of the Key Biscayne off Australia, and the fire-mottled Sea Quest's attempt to walk into Nigeria.

National governments subcontracted strategy to the UN Platform Event Repulsion Unit: scientists, engineers, theologians and exorcists, soldiers, veterans like Dughan of those first encounters. He learnt the new motions, the vastly swaying skittishness and violence of the revenant rigs. His UNPERU colleagues strove to decode this hydrocarbon Ragnarok. Twice, Dughan boarded pitching, stinking decks to transmit to them close-up footage, from which they learnt nothing. They tried to figure out what economies of sacrifice were being invoked, for what this was punishment. Ruined, lost, burnt, scuttled rigs were healing on the ocean floor and coming back. Platform, jackup, semi-submersible: all the lost.

After the semi-sub Sea Quest retreated under heavy attack, descending back into the Gulf of Guinea, UNPERU turned its attention and resources to the Ocean Ranger, stalking the Atlantic seabed. So when, shortly after its brief first appearance, the Sea Quest reemerged, and continued its interrupted journey into the oil-fouled Delta, they were not there to intercept. Word reached Dughan and his crew en route to Canada. They came back fast, turning their plane in mid-air.

They were escorted inland by ex-M.E.N.D. guerrillas with peerless local savvy, hastily pardoned by the Nigerian government. They followed the oil rig's mashed-up trail, the rainbow-filmed liquid spoor, the tripod crater prints. In retrospect, certain qualities of the disturbed interior foreshadowed more dramatic instabilities that later petrospectral presences would bring.

Bursts from the derrick known to have been destroyed in the rig's last moments, now heat-twisted but regrown, flared above the forest. The soldiers reached the edge of the clearing the Sea Quest had stamped. They held fire and watched.

Bracing on struts still thick with coraline outgrowths, the Sea Quest settled into the mud. It started its drill. Pushed it into the ground and down.

For a long time it was still but for an occasional swaying tremble of some stuff low-hanging from it. Should we attack? officers kept asking. Dughan shook his head. He checked Unit Beta's images, the Ocean Ranger off the Labrador coast, the tip of its tower a dorsal fin. The stomach-dropping video was proof for which no one had known they were waiting: that below the waves the rigs also walked.

High overhead the Sea Quest's flame was all but out: a dirty smoke plume took its place as cockscomb. 'It's drinking,' one of the soldiers had said to the shake of its pumps. After four hours Dughan sent out a team, joined them when the rig did not respond. Another four and they went closer skill. Eleven hours after the drilling had started, the tower breathed fire again and shook and abruptly pulled its drill from the mud.

The birds that had settled to peck at its deepwater carrion were gone in one cloud. The soldiers made it back to the treeline. The Sea Quest rose on shaft-legs like some impossible dreaming pachyderm. It retraced its stamping passage, trees in its shadow.

The UNPERU team followed. They tried to keep locals away. They were the oil rig's escorts, back to the sea. The platform walked slowly into the water, paused a while in the chop, descended.

* * *

A clutch of dead trees jutted from the scrub like bleached markers of where Covehithe ended. A ribbon of crabgrass separated the sea and shore from Benacre Broad. A cold marsh, a roosting place for birds. The Petrobras approached.

Dughan hesitated and his daughter saw him do so. He wanted to go closer, but there was not enough cover.

The rig. It closed on her and she stopped breathing. It came near enough that she felt the envelope of cold air it brought, smelled abyssal rot and chemical cracking. Spray hit her. The weary factory's spray. It giant-walked by her hiding place sending all those Suffolk birds away, hauled into the fens to squat like a monument that had always been there.

It braced. A percussion of chains, the crack of old shells, and its drill descended.

The first platforms had returned close to where they went down. But then Interocean II had emerged not in the North Sea but in the harbour of a hastily evacuated Oporto, stepped daintily over the seawall like someone crossing a stile. Sedco 135F rose in the Galapagos, far from the Bay of Campeche. The many-legged barge Ocean Prince came up not in Dogger Bank but Sardinia. Revisitors might come, drill, go back to the water, even come up again, anywhere.

Dughan's daughter had got away from him, got closer to the visitor. Had he not noticed her go? Before he knew it, he might have said, she was gone. It might be true. She was pressed against one of the dead trees. Beyond her was Petrobras, like a failed city block. Dughan whispered her name. She watched the dead and come-back rig boring.

He went to her, of course. Exhilarating to exit the treeline. He was quickly there, looking with her through barkless branches. The platform was calm, its fire low. It shivered, only, tinily, all its thousands of tons. Ripples passed over the wetland, not outward but in, circles decreasing, shrinking to that point where the shaft entered the ground.

They watched. After many seconds, Dughan felt something pressed to his back. He had long enough before anyone spoke to be surprised that whoever this was had got so close without him hearing. He blamed the reek and weird industry he was watching. A voice said: 'You move and I'll fucking kill you.'

When the lost rigs of the world came back, old hands claimed they had seen in the motion of the drills something reversed. Dughan doubted it: shuddering was shuddering. But most of the places where the rigs went there were no oil fields. It might have been that they were sniffing other things than oil to sustain them, but that was not so.

'Turn around,' the voice said. The uniformed man who faced them was young and afraid. With a weapon pointed at him, old techniques, muscle memory came back and twitched Dughan's fingers, but he stayed still.

The man scanned them. No RPGs, no mortars, not even smaller arms. They were not oleophobe fanatics here to attack the Petrobras, nor Oil Firsters, here to kill him, his colleagues and all those who came to investigate or exploit, in their parlance, the visitations.

'Who the fuck are you?' The guard glanced over their heads at the shuffling rig. He was whispering, though Dughan knew it would make little difference now.

'We're just here to watch,' the girl said gently. She was taking care of him. 'My dad brought me here to watch is all. Just to see it.'

The guard searched them, cack-handedly. Dughan silently counted the times he could have disarmed him. The man found only binoculars, torch and cameras. He frowned at their pictures of Suffolk, of Punch-and-Judy shows, of roadside oddities. No contraband sights. 'Jesus!' he said. 'Move, then.'

Behind them the rig shifted and he cringed at the great squelch. 'What are you even doing?' he said when they had retreated to the living trees. 'Do you have any idea how dangerous this is?'

'I'm sorry, it was me,' she said. 'I just really wanted to see it up close and I begged him. I'm really sorry.'

The man wiped his forehead. 'Let me tell you something,' he said. 'Last time there was one of them here, down by Camber Sands?' The Adriatic IV. Dughan didn't say it. 'There was a couple of young lads got in. Got past us. I shouldn't tell you. They were larking about. Taking pictures and that. Anyway you know what happened? They had a dog with them and it got too close, and it spooked the rig and it moved. Midway through.' He waved through the copse. 'It trod on the dog.'

Dughan looked back up at the Petrobras's subdued high burning.

'Now come on.' The guard beckoned. 'Let's get back.'

When their feet hit the beach sand, the girl said to him, 'How long'll it be?' Just close enough to the inlet and troughs gouged by the rig's passing to afford a sightline into the broads, headlights flashed. The jeeps were visible a moment, and people.

'It'll be there half a day at least,' the man said. 'And it's a few months later it'll all kick off.' He even smiled.

'You know,' he said, 'I don't know, you might probably be a bit old for it but there's like a kids' club they have here. They have activities and that.'

'You saw some once, didn't you, dad?' Dughan was not angry when she said that. He marvelled, really, at her.

All its research notwithstanding, UNPERU expressed as much shock as the rest of the world when, over a year after the Ocean Ranger's visit, up from the still-recovering Newfoundland ground into which it had pushed its drill, the first clutch of newly-hatched oil rigs had unburied themselves.

They had emerged into the night, shaking off earth. Stood quivering on stiffening metal or cement legs. Tilted tiny helipads. Tottered finally for the sea.

'How big are they, Dad?' she said.

'You've seen films,' he said. 'As big as me.'

Dughan had gone back to Nigeria. He had waited for months, on the vagaries of gestation. At last the monitors in the delta picked up evidence of subterranean shifts. Over many hours, long before dawn, he had watched unsteady six-foot riglets burrow up out of the forest dirt. Seven of them, of all different designs; buildings, supports, struts, derricks. They waited, swaying like new calves, still wet from their tarry sacs, swinging umbrella-sized cranes.

He helped to capture two, and to usher the rest safely to the water, where the baby rigs had been tagged and released to scuttle below the waves, escorted by divers as far down as the divers could go. The two captives were taken to hangars where great tanks of brine waited. But they sickened within days and died, and fell apart into scrap and rubble.

The Oporto authorities pumped poisons into the university grounds where the Interocean II had drilled and left the earth slick and soupy. Whether that was what kept its brood from being born was never clear: those eggs were not recovered. In other coastal cities, neonate oil platforms did emerge, to gallop hectic and nervy through the streets, spreading panic.

Only the most violent post-return decommissioning could stop all this, only second deaths, from which the rigs did not come back again, kept them from where they wished to go, to drill. Once chosen, a place might be visited by any one of the wild rigs that walked out of the abyss. As if such locations had been decided collectively. UNPERU observed the nesting sites, more all the time, and kept track of the rigs themselves as best they could, of their behemoth grazing or wandering at the bottom of the world.

'What activities do they do in this club?' the girl said.

'Oh.' The guard shrugged. 'Stuff like, you can see the eggs on a live feed. They'll be digging down to them and they'll put cameras and thermometers and whatever. Sometimes you can even see movement through the shells. And there's colouring books and games and that.' He smiled again. 'Like I say, it's too young for you.'

They laid eggs, so, many people said, they must have sex. There was no logic there. They were oil rigs. Dughan thought the belief exoneration of the strange prurience that endlessly turned on monoliths rutting miles down. An inhuman pornography of great slams and grinding, horrified whales veering from where one rig mounted another, warmed by hydrothermal vents.

'And no one knows what happens to the young, isn't it, dad?'

Other guards came to meet them. Half welcoming, half peremptory. Dughan recognised none. Behind the security were the few tourists lucky to have been nearby, at accredited hotels, when Petrobras's heavy steps had registered on the scanners.

'No one knows yet,' Dughan said to his daughter. 'They're still very young. They're little and the sea's very big. They've got a lot of growing to do.'

A guide was in the middle of a spiel. 'We'll come back in the morning, when it's finished laying,' she said. 'You can bring your cameras then – no danger then if you forgot to turn your flash off.' People laughed.

'What's wrong?' Dughan whispered.

'Do you think it's true what he said?' the girl whispered. 'About the dog? That's horrible.' She made a face. He stared not at the twitching Petrobras P36 with its concrete in the mere, not at its drill ovipositor injecting slippy black rig eggs into England, but at the sea. 'Maybe he was lying to scare us,' the girl said.

Dughan turned and took in the length of Covehithe Beach. They were out of sight, but he looked in the direction of the graveyard, and of St Andrew's stubby hall where services continued within the medieval carapace, remains of a grander church fallen apart to time and the civil war and to economics, fallen ultimately with permission.

© China Miéville 2011

 Supported by the National Lottery through Arts Council England

 China Miéville's Embassytown will be published in hardback and ebook on 6 May 2011