So, no floating platforms, then. Johanson decided to quiz him about the robot.

'It's a Victor 6000, a remotely operated vehicle, or ROV,' Alban explained. 'It's got a working depth of six thousand metres and can stay under water for days at a time. We guide its movements from the boat – a cable leading up to the control room delivers its data simultaneously. The next trip is a forty-eight-hour recce. We'll get it to fetch you a handful of worms – Statoil prides itself on preserving biodiversity.' He paused. 'What do you make of the creatures?'

'It's too early to say,' said Johanson.

There was a clunk and Johanson watched as the boom hoisted Victor off the deck.

'Follow me,' said Alban. They headed amidships towards five shed-sized containers. 'Most vessels aren't equipped for using Victor, but since we could accommodate it, we borrowed it from the Polarstern?

'What's in the containers?'

'The hydraulic unit for the winch, plus some other bits of machinery. The one at the front is home to the ROV control room. Mind your head.'

They stepped through a low door. Inside, over half of the space was taken up by the control panel and twin banks of screens. Some were switched off, but the rest showed navigational data and operational feedback from the ROV. A group of men sat with Lund at the consoles.

'The guy in the middle is the pilot,' Alban murmured. 'To his right, the co-pilot operates the articulated arm. Victor's very sensitive and precise, but the operator has to be equally skilled in telling it what to do. The next seat along belongs to the coordinator. He maintains contact with the watch officer on the bridge to ensure that the vessel and the robot work together. The scientists are over there, with Tina. She'll operate the cameras and record the footage.

'Are we ready?' he asked her.

'Prepare to lower,' said Lund.

One after another the blank screens lit up. Johanson could make out sections of the stern, the boom, the sky and the sea.

'From now on we can see what Victor sees,' said Alban. 'There are eight separate cameras, one main camera with zoom, two piloting cameras and five others. The picture quality's amazing – sharp images and luminous colours even several thousand metres below the surface.'

The robot descended and the sea loomed closer. Water sloshed over the camera lens and Victor continued downwards. The monitors showed a blue-green world that gradually dimmed.

The control room was filling with people, men and women who'd been working on the boom.

'Floodlights on,' said the coordinator.

The area around Victor brightened, but the light remained diffuse. The blue-green paled, and was replaced by artificially lit darkness. Small fish darted into the picture, then the screen filled with bubbles. Plankton, thought Johanson. Red-helmet and transparent comb jellyfish drifted past.

After a while the swarm of particles thinned. The depth sensor recorded five hundred metres.

'What's Victor going to do down there?' asked Johanson.

'Test the seawater and sediment, and collect a few organisms,' said Lund, focusing on the screen, 'but the real boon is the video footage.'

A jagged shape came into view. Victor was descending along a steep wall. Red and orange crayfish waved delicate antennae. It was pitch black in the depths, but the floodlights and cameras brought out the creatures' natural colours vividly. Victor continued past sponges and sea cucumbers, then the terrain levelled off.

'We made it,' said Lund. 'Six hundred and eighty metres.'

'OK.' The pilot leaned forwards. 'Let's bank a little.'

The slope disappeared from the screens. For a while they saw nothing but water until the seabed emerged from the blue-black depths.

'Victor can navigate to an accuracy of within less than a millimetre,' said Alban.

'So where are we now?' asked Johanson.

'Hovering over a plateau. The seabed beneath us contains vast stores of oil.'

'Any hydrates?'

Alban looked at him thoughtfully. 'Sure. Why do you ask?'

'Just interested. So it's here that Statoil wants to build the unit?'

'It's our preferred site, assuming there aren't any problems.'

'Like worms?'

Alban shrugged.

The Frenchman seemed to have an aversion to the topic, thought Johanson. Together they watched as the robot swept over the alien world, overtaking spindly legged sea spiders and fish half buried in the sediment. Its cameras picked up colonies of sponges, translucent jellyfish and miniature cephalopods. At that depth the water wasn't densely populated, but the seabed was home to all kinds of different creatures. After a while the terrain became pockmarked, coarse and covered with what appeared to be vast whip marks.

'Sediment slides,' said Lund. 'The Norwegian slope has seen a bit of movement in its time.'

'What are the rippled lines here?' asked Johanson. Already the terrain had changed again.

'They're from the currents. Let's steer round to the edge of the plateau.' She paused. 'We're pretty close to where we found the worms.'

They stared at the screens. The lights had caught some large whitish areas.

'Bacterial mats,' said Johanson.

'A sure sign of hydrates.'

'Over there,' said the pilot.

The screen showed a sheet of fissured whiteness – deposits of frozen methane. And something else. The room fell silent.

A writhing pink mass obscured the hydrate. For a brief moment they saw individual bodies, then the writhing tubes were too numerous to count. Pink flesh and white bristles curled under and over each other.

There was a sound of disgust from the men at the front. Conditioning, thought Johanson. Most humans disliked crawling, wriggling, sliding creatures, even though they were everywhere. He pictured the hordes of bugs swarming over his skin, and the billions of bacteria in his belly.

But, despite himself, Johanson was unsettled by the worms. The pictures from the Mexican Gulf had shown similarly large colonies, but with smaller worms sitting calmly in their holes. These worms never stopped slithering over the ice, a vast heaving mass that obliterated the surface.

'Let's zigzag round,' said Lund.

The ROV cut through the water in a sweeping slalom movement, the worms ever-present.

Suddenly the ground fell away. The pilot steered the robot to the edge of the plateau. Even with the combined power of eight strong floodlights, visibility was limited to just a few metres, but it was easy to imagine that the worms covered the length of the slope. To Johanson they seemed even bigger than the specimens Lund had brought into the lab.

The screens went dark. Victor had launched itself over the edge. There was a hundred-metre vertical drop to the bottom. The robot raced on at full speed.

'Turn,' said Lund. 'Let's take a look at the wall.'

Particles danced in the beam of the floodlights. Then something big and bright billowed into the frame, filling it for an instant, then retreating at lightning speed.

'What was that?' Lund called.

'Turn back!'

The ROV retraced its steps.

'It's gone.'

'Circle!'

Victor stopped and started to spin, but there was nothing to see, apart from impenetrable darkness and showers of plankton glittering in the light.

'There was something out there,' said the coordinator. 'A fish maybe.'

'Bloody big one,' growled the pilot.

Lund turned to Johanson, who shook his head. 'No idea.'

'OK. Let's go a bit deeper.'

The ROV headed towards the slope. A few seconds later a steep wall of seabed loomed into view. A few raised areas of sediment were visible, but the rest was covered with the now-familiar pink masses.

'They're everywhere,' said Lund.

Johanson joined her. 'Have you got a chart of the hydrate deposits here?'

'The area is full of methane – hydrates, pockets in the rock, gas seeping through the seabed…'