His strength was running out, the fingers of his right hand let go of the metal. There was a sickening jerk and he was hanging by one arm. The derrick was toppling and the gas flame on the boom was no longer shooting out across the water but rising vertically into the dark sky.

Then everything exploded in a fiery, incandescent cloud, and Jörensen was cast into the sea. He didn't feel the pain in his lower arm, where the blast had severed his hand, leaving it hanging in the metal. Before the spiral of flames could engulf him, the tsunami hit the sinking platform. Gullfaks C was blasted to pieces, the concrete pillars plunging into the sea.

Granddad, tell us a story…

OSLO, Norway

The woman frowned as she listened to him. 'What do you mean?' she asked. 'A kind of chain reaction, did you say?'

She was on the Ministry of Environment's Disaster Management Committee, and she was used to being confronted with the most outrageous theories. But she knew of the Geomar Centre, which didn't usually make ludicrous claims. She focused on understanding what the German scientist on the telephone was trying to say.

'Not exactly,' said Bohrmann. 'It's simultaneous. The damage is occurring all along the slope. It's taking place everywhere at exactly the same time.'

The woman swallowed. 'And… which areas will he hit?'

'That depends on the location of the break and how far it extends. Still, a large proportion of the coast, I'd say. Tsunamis stretch thousands of kilometres. We're informing anyone in the vicinity- Iceland, the UK, Germany, everyone.'

The woman stared out of her office window. She was thinking of the oil platforms, stranded in the sea. Hundreds of them, as far north as Trondheim.

'What will happen to the coastal regions?' she asked dully.

'You should make plans to evacuate.'

'And the offshore industry?'

'As I said, it's hard to predict. If we're fortunate, there'll be a series of small-scale landslides. In that case, the platforms might wobble, but basically they'll be fine. On the other hand, if. . .'

The door opened and a man rushed in. His face was white. He thrust a sheet of paper in front of her and signalled to her to end her conversation. She picked up the printout and scanned the short text. It was the transcript of a radio message from a ship. The Thorvaldson.

As she read on, she felt as though the ground were slipping away from her.

'The warning signs are already there,' Bohrmann was saying. 'In the event of it happening, anyone living on the coast should know what to expect. Tsunamis make their presence known before they strike. When the wave is approaching, the sea level rises and falls. It's rapid, and it happens several times, so you'd notice if you knew what to look for. After ten to twenty minutes the water retreats from the shore. Reefs and rocks become visible. You start to see parts of the seabed that are usually covered. That's the last warning. Then you must head for higher ground.'

The woman didn't speak. She'd almost stopped listening. A few minutes earlier she'd been trying to imagine what would happen if the man was telling the truth. Now she was picturing what was taking place that second.

SVEGGESUNDET, Norway

Lund was dying of boredom. The kitchen assistant had switched on the espresso machine for her benefit and the coffee had been delicious. And despite the stormy weather and poor visibility, the view of the sea through the panoramic windows while she drank it had been amazing. But Lund found the wait unbearable.

A blast of cold air hit the room.

'Hello, Tina.'

It was a friend of Kare's, Ake. He ran a successful boat-hire business in Kristiansund that made a lot of money in the summer.

They talked a bit about the weather. Then Ake asked, 'So what are you doing here? Visiting Kare?'

'That was the plan.' She smiled wryly.

Ake looked at her in surprise. 'So where is he?'

'It's my fault. I'm early.'

'Give him a call, then.'

'I've tried. Voicemail.'

'Of course.' Ake slapped his forehead. 'I'd forgotten. He won't have any reception.'

Lund sat up. 'You know where he is?'

'Sure, I was with him. We took a trip to Hauffen.'

'The distillery-?'

'That's right. He's buying spirits. We sampled one or two, but you know Kare – he drinks less than a monk during Lent.'

'Is he still there?'

I left him chatting with them in the cellars. You should head over. Do you know where Hauffen is?'

Lund did. The little distillery produced an excellent aquavit reserved for the Norwegian market. It was on a low plateau to the south, about ten minutes away on foot. She could be there in two minutes by car, if she took the inland road. But somehow the thought of a short walk appealed to her. Besides, she'd sat in the jeep long enough already. I'll walk,' she said.

'In this weather?' Ake pulled a face. 'Well, it's up to you. Don't blame me if you get webbed feet.'

'Better than putting down roots.' She stood up. 'See you later. I'll bring him back here.'

Outside she pulled up her jacket collar, walked down to the beach and setoff. On good days the distillery was clearly visible. Right now, it was just a faint grey outline through the slanting rain.

As she left the Fiskehuset behind her, she gazed out to sea. She must have been mistaken earlier. She'd thought the stony beach seemed longer than usual, but now it looked the same. No … it might be a bit smaller.

She shrugged and carried on.

When she arrived at the distillery, soaking wet, there was no one in the foyer. On the far side a wooden door stood open. Light shone up from the cellars. She went straight down the stairs. There she found two men, leaning against the barrels, chatting, each with a glass in his hand. They were the two brothers who owned the distillery – friendly old men with weather-beaten faces. Kare was nowhere to be seen.

'Sorry,' said one. 'You've just missed him. He left a few minutes ago.'

'Did he come on foot?' she asked. Maybe she could catch up with him.

'In the van. He bought a few bottles. Too many to carry.'

'Was he going back to the restaurant?'

'That's where he said he was heading.'

'Thanks.'

'Hey, hang on a minute. You can't visit a distillery and leave before you've had a drink.'

'It's very kind of you, but-'

'He's right, you know,' his brother said eagerly.

'I-'

'Come on, you'll catch your death out there. Let's get a drop of something warm inside you first.'

'OK' she said. Just one.

The brothers grinned triumphantly. The war of attrition had been won.

SHETLAND ISLANDS, Great Britain

The helicopter was preparing to land. Johanson looked out of the window. They'd just flown over the cliffs, following the coastline in the direction of the little landing-field where Karen Weaver would he waiting. Towards the east of the island the cliffs sloped downwards to end in a sweeping bay. From there the landscape was flat. An endless succession of sand and pebble beaches separated the water from barren moorland and long rolling hills with roads etched between them like scars.

The helipad, which was rather a grand term for the rough circle of gravel surrounded by grey-green moorland, belonged to a marine research station whose crooked, windswept huts housed half a dozen scientists. A narrow road led down from the hills and stopped at a jetty. Johanson couldn't see any boats. Two jeeps and a rusty VW bus were parked next to the buildings. Weaver was working on an article on seals, which was why she'd chosen the spot. She lived in one of the huts, accompanied the scientists on their expeditions and joined in on their research dives.