'Nice thought,' said Bohrmann. 'OK, La Palma is relatively manageable, but what about the American continental slope? You can't seriously be planning to use one suction tube to clear all of that seabed.'

'Course not.' Evidently Frost was astounded by the idea. 'That speech was supposed to be motivating!'

Bohrmann turned towards the monitors. He hoped to God the scheme would work. But even if they got rid of the worms, they still couldn't be certain how many bacteria had already been deposited in the ice. Deep down he was worried that it was too late to prevent the collapse of Cumbre Vieja. At night he had terrifying visions of a huge dome of water rushing over the ocean towards him. But he was doing his best to be optimistic. Somehow they'd make it work. And maybe the others on the Independence would persuade the unknown enemy to see sense. If the yrr were capable of destroying an entire continental slope, maybe they could repair one.

Frost gave another impassioned speech, denouncing the enemies of mankind and heaping praise on the technicians from De Beers. Then he signalled for the tube and the lighting system to be lowered.

THE LIGHTING UNIT was a gigantic concertinaed floodlight scaffold. Suspended over the waves from the arm of the crane, it consisted of a compact package of metal pipes and struts, ten metres long and crammed with lights and cameras. The crane lowered it into the water and it vanished beneath the surface, linked to the Heerema with a fibreoptic cable. After ten minutes Frost glanced at the depth gauge and said, 'Stop.'

Van Maarten relayed the command to the operator. 'You can open it up now,' he added. 'Half-way at first. If there's nothing in the way, we'll open it entirely.'

Four hundred metres below the surface, an elegant metamorphosis was taking place. The metal package unfolded into a framework of scaffolding. The area seemed clear, and soon a lattice-like frame, the size of half a football pitch, was hanging in the water.

'Ready and waiting,' said the operator.

Frost glanced at the control panel. 'We should be right in front of the flank.'

'Lights and camera,' instructed van Maarten.

The frame was lit with row upon row of powerful halogen lamps, while the cameras rolled into action. A gloomy panorama appeared on the monitors. Plankton drifted across the screens.

'Closer,' said van Maarten.

The scaffold moved forwards, pushed by two swivelling propellers. After a few minutes a jagged structure rose out of the darkness. As they drew closer it became a black wall of unevenly sculpted lava.

'Down a bit.'

The scaffold sank. The operator navigated the depths with utmost caution, until a terrace-like protrusion showed up on the sonar. Without warning, a ridge appeared on the screen, so close it seemed almost in touching distance. Its surface was covered with wriggling bodies. Bohrmann stared at the eight monitors with a sinking feeling in his stomach. He was face to face with the nightmare that had haunted him since the collapse of the Norwegian slope. If the entire flank looked the same as the forty metres that the floodlights had wrested from the darkness, they could turn round and go home.

'Evil bastards,' growled Frost.

We're too late, thought Bohrmann.

Immediately he felt ashamed of himself for fearing the worst. No one could tell whether the worms had unloaded their cargo of bacteria or whether there'd be enough to do any real harm. Besides, there was still the unknown factor that had provided the final trigger. It wasn't too late. But they didn't have time to hang around.

'All right, then,' said Frost. 'Let's raise the unit and tilt it by forty-five degrees so we get a better view. And then it's time to lower the tube. I hope it's hungry.'

'Ravenous,' said van Maarten.

AT MAXIMUM EXTENSION, the suction tube stretched half a kilometre into the depths, a segmented, rubber-insulated monster, measuring three metres in diameter and culminating in a gaping mouth. Its opening was armoured with floodlights, two cameras and a number of swivelling propellers. From the Heerema, the end of the tube could be steered up and down, forwards, backwards and sideways. The monitor in the driver's cab combined footage from the lighting scaffold with images from the tube, providing a generous view of the overall picture. But although the visibility was good, operating the joysticks required sensitive fingers and a co-pilot to make sure that nothing was missed.

Time ticked by as the tube fell through the impenetrable darkness. Its floodlights were switched off. Then the lighting scaffold came into view. At first it was just a faint glimmer in the pitch-black water, then its glow intensified, taking on a rectangular form and finally sculpting the terrace out of the rock. It was so big that Bohrmann was reminded of a space station. The tube continued to sink, nearing the milling mass until the monitors were covered with writhing bristly worms.

There was a breathless silence in the control room.

'Amazing,' whispered van Maarten.

'A good cleaner doesn't stand about admiring the dirt,' Frost said grimly. 'It's about time you switched on your vacuum-cleaner and got rid of them.'

THE SUCTION TUBE was really a suction pump that created a vacuum, so that anything that passed before its mouth was swallowed inside. They threw the switch, but nothing happened. The pump evidently needed time to warm up – or that was what Bohrmann hoped. The worms went about their business uninterrupted. Disappointment swept round the room. No one said a word. Bohrmann fixed his eves on the two monitors displaying the tube. What was the problem? Was the tube too long? Or the pump too weak?

While he searched for an explanation, the picture changed. Something was tearing at the worms. Their bodies rose, then lifted vertically in the water, quivering frantically… They rushed towards the cameras and were gone.

'It's working!' Bohrmann shouted, and punched the air. He felt like dancing and turning cartwheels.

'Hallelujah!' Frost nodded vigorously. 'Oh, Lord, we're going to cleanse the world of evil. Sheesh!' He tore off his baseball cap, ran his hands through his hair and put the cap back on. 'Those critters won't know what's hit them.'

The worms were sucked into the tube so quickly and in such numbers that the picture faded to a flicker as sediment rose in swirls from the terrace.

'Further to the left,' said Bohrmann. 'Or the right. Doesn't matter which way, as long as you keep going.'

'Why don't we zigzag over the terrace?' suggested van Maarten. 'We could vacuum the floodlit zone from one end to the other. Then, once it's clear, we'll move the lights and the tube and start on the next forty metres.'

'Makes sense. Let's do it that way.'

The tube wandered over the terrace, pulling in worms as it went and causing such turbulence that the rock disappeared in clouds of sediment.

'We'll have to wait until the water settles to see what we've achieved,' said van Maarten, sounding relieved. He gave a deep sigh, and leaned back serenely. 'But my guess is that we'll all be pretty pleased.'

INDEPENDENCE, GREENLAND SEA

Dong! Trondheim church bells on a Sunday morning. The chapel in Kirkegata Street. Bathed in sunshine, the little steeple was stretched confidently into the sky, casting its shadow over the ochre-coloured house with its pitched roof and white steps.

Ding dong.

He buried his head in the pillow. As though church bells could dictate when it was time to get up. Fat chance! Had he been drinking last night? He must have been in town with some colleagues from the faculty.