'At four thousand metres the hull will implode,' Alban corrected him. 'It's cleared for a maximum of a thousand.'

'I know the facts. And we're only going nine hundred metres. What could possibly go wrong?'

'I don't know. But the seabed's changed. The water's filling with gas and the processor won't show up on sonar. God only knows what's going on down there.'

'Maybe there's been a slide. Or a partial collapse. If we're unlucky, there'll have been some subsidence. It happens, you know.'

'I guess.'

'So, what's the problem?'

'The problem,' said Alban, losing his temper, 'is that a robot could do the job for you. But – oh, no – you have to play the hero.'

Stone pointed at his eyes. 'You see these? They're still the best way of working out what's wrong. That's how problems are solved. You take a good look, then you fix them.'

'Fine.'

'So when are we going down?' Stone glanced at the time. 'OK, another half-hour. No, twenty minutes.' He waved at Eddie, who raised his hand and turned back to the controls. Stone grinned. 'What are you worried about? We've got the best pilot around. I'll even steer the thing myself, if I have to.'

Alban didn't reply.

'I'm going to take one last look at the dive plan. I'll be in my cabin if you need me. And do me a favour, Jean, find those bloody camera people. Anyone would think they'd fallen overboard.'

Trondheim, Norway

Could he really be out of aftershave? Impossible. Sigur Johanson kept a stockpile of life's little luxuries. He never ran out of wine or grooming products. Surely he had another bottle of Kiton eau-de-toilette.

He went back to the bathroom and rummaged through the cabinet. He needed to get a move on. The helicopter was waiting at Statoil's research centre to transport him to his meeting with Karen Weaver. But for someone who cultivated dishevelment, packing was complicated: neat people never had to bother with deliberations about which shade of jacket clashed to just the right effect.

Hidden behind two tubs of styling wax he found what he was looking for. He put the bottle in his wash-bag, then squeezed it into his suitcase, with some poetry by Walt Whitman and a book about port, then let it click shut. It was an expensive bag of the kind popular at the beginning of the nineteenth century among rich Londoners, who used them for weekend jaunts. The leather straps had been sewn by hand.

THE FIFTH DAY!

Had he packed the CD? All the material supporting his incredible idea about the plan was on it. Perhaps there'd be a chance to discuss it with the journalist. There it was, buried under a pile of shirts and socks.

He left his house in Kirkegata Street with a spring in his step, and crossed the road to his jeep. For some reason he'd been raring to go since first thing that morning. There was something almost hysterical about his energy. Before he started the engine he took a last glance at the house.

Suddenly he realised that he was trying to distract himself. His hyperactivity was an attempt to ward off thought, like whistling in the dark. His hand hovered beside the ignition as he gazed towards the city. A damp mist was hanging over Trondheim, blurring its contours. Even his house on the other side of the street seemed flatter than usual. It looked almost like a painting.

What happened to the things you loved?

He had spent many hours in front of Van Gogh's paintings, feeling an inner peace as though the artist hadn't suffered from suicidal depression. Nothing could destroy the painting's impression. Of course, a picture could be destroyed but as long as it existed, it was a definitive moment captured in paint. The sunflowers would never fade. The Langlois Bridge at Aries could never he bombed. The image of horror would always be horrifying; the image of beauty stayed beautiful forever. Even the portrait of the man with the angular features and the white bandage over his ear had something comfortingly constant about it. At least in the picture he couldn't become unhappier, he couldn't age. The man in the painting was eternal. In the end he'd triumphed over those who'd tortured him or couldn't understand him. With the help of a paintbrush and his genius he'd outwitted them all.

Johanson looked at his house. If only it were a picture, and I was in it too, he thought. But he didn't live in a picture, and his life wasn't a gallery where he could pace out his past in a matter of steps. His house by the lake would make a fabulous picture, then a study of his wife, and pictures of all the other women he'd known, the friends he'd had – and Tina Lund, of course. Tina, hand in hand with Kare Sverdrup, at peace for all time.

He was assailed by a dull sense of loss. The world is changing, he thought. They're closing ranks against us. Somewhere something has been decided, and we weren't part of it. Humanity wasn't there.

He started the engine and drove away.

KIEL, Germany

Erwin Suess walked into Bohrmann's office with Yvonne Mirbach in tow. 'Call Johanson,' he said, 'Now.'

Bohrmann had known the Geomar director for long enough to grasp that something out of the ordinary had happened. 'What's wrong?' he asked, although he felt certain he knew.

Mirbach pulled up a chair and sat down. 'We've run through different scenarios on the computer. The collapse will take place sooner than we thought.'

Bohrmann's brow furrowed. 'Collapse? Last time we weren't even sure it would come to that.'

'The evidence doesn't look good,' said Suess.

'Because of the consortia?'

'Yes.'

Bohrmann felt a cold sweat break out on his forehead. It's not possible, he thought. They're only bacteria – minute, microscopic organisms. He knew he was thinking like a child: how could something so small destroy a layer of ice a hundred metres thick? There was no way. What difference could a microbe make to thousands of square metres of seabed? None. It was inconceivable, unreal. It couldn't happen. Scientists knew relatively little about consortia, but it was clear that various micro-organisms worked in symbiotic partnerships at the bottom of the ocean. Sulphur bacteria, for example, allied themselves with archaebacteria – odd single-cell microbes that numbered among the oldest forms of life. The symbiosis was extremely successful. Consortia of this type had first been discovered on hydrates only a few years previously. The sulphur bacteria took up oxygen to break down nutrients, including nitrogen, carbon dioxide and other carbon compounds, which were released by the archaea as they feasted on their delicacy of choice.

Methane.

The symbiosis meant the sulphur bacteria also lived off methane, although they never got a taste of it. Most methane was found in the oxygen-free sediment, and sulphur bacteria needed oxygen to survive. Archaea didn't. They broke down methane without oxygen, and could carry on doing so several kilometres beneath the seabed. Scientists estimated that archaea converted 300 million tonnes of marine methane each year, which probably benefited the climate: broken-down methane couldn't escape into the atmosphere as a greenhouse gas. In that respect, archaea were a kind of environmental task-force.

Provided they stuck to the seabed.

The trouble was, archaea also lived in symbiosis with worms, and the mutant worm with monstrous jaws was covered with consortia of archaea and sulphur bacteria, living in its guts and on its skin. With every metre it descended into the ice, the bacteria were transported further into the hydrates, where they destroyed the frozen layers from the inside, spreading like a cancer. Before too long the worm would perish, and so, too, the sulphur bacteria, but the archaea would chomp their way steadily through the ice, turning the dense layer of hydrates into a porous friable mass. Gas would leak out to the surface.