It was imploding, like a Big Bang in reverse. Everything was sucked towards its centre, which grew steadily brighter and denser. Flashes of light shot out, forming complicated patterns. The cloud was disappearing into its mid-point at incredible speed, drawn into a turbulent whirlpool, and then…

'This can't be happening,' said Oliviera.

On the other side of the glass there was now a spherical object the size of a football. A blue-tinged mass of matter, made of luminous pulsating jelly.

They'd found the creatures.

And they'd become one.

FLAG COMMAND CENTER

'Single-cell organisms,' Johanson said. 'They're single-cell organisms!' He was incredibly excited. Rubin shifted on his chair and nodded vigorously, while Johanson paced up and down. He could never have stayed seated at a time like this. 'Until now we've assumed that the jelly and the cloud are two separate entities, but they're one and the same. They're a network of unicellular beings. It's not just a case of the jelly changing shape – it can disintegrate entirely, and get back together in a flash.'

'The unicellular whatsits can disintegrate?' queried Vanderbilt.

'Of course not! The single-cell organisms combine to form the jelly and the cloud. When we opened the crabs, we found blobs of the jelly inside them. We only managed to catch hold of one and all the others disappeared. Then we lost the captive too. It vanished without trace. I can't believe I didn't work it out straight away. It's obvious that you can't keep single-cell organisms in a cage. And you're hardly going to see them with the naked eye! The chamber was lit internally, which meant there was no sign of any bioluminescence. We had the same problem in Norway. A huge thing appeared in front of our cameras. At the time we saw a pale surface, lit up by Victor's floodlights, but in reality it was glowing. It was glowing because it was made up of an enormous confederation of luminescent microbes. The creature we've got swimming about in the tank right now is a combined mass of jelly we let out of those crabs.'

'Well,' said Anawak, 'that would explain the shapeless creature on the keel of the Barrier Queen, the blue cloud near Vancouver Island…'

'Of course – your URA footage of the whales… Well, most of those cells would have been floating freely in the water, but others combined to form tentacles. They must have been injecting themselves into the heads of the whales, and-'

'Hang on a minute.' Li raised her hand. 'The jelly was already inside their heads.'

'OK, then.' Johanson thought for a moment. 'Well, some kind of connection took place. I bet that's how the jelly finds its way inside. Maybe we were witnessing some kind of exchange: old jelly out, new jelly in. Or it could have been a kind of check-up. Maybe the gunk in the brains was handing something to the cells outside.'

'Information,' said Greywolf.

'Why not?' exclaimed Johanson.

Delaware wrinkled her nose. 'You mean, they can take on any size at all? They can be as big as they need to be?'

'Any size and any shape.' Oliviera nodded. 'To steer a crab, you need only a handful. But the thing near the whales off Vancouver Island was the size of a house so-'

'That's why our discovery is so important,' Rubin cut in. He leaped to his feet. 'The jelly is a raw material that serves to accomplish different tasks.'

Oliviera looked put out.

'I've taken a close look at the footage from the Norwegian continental shelf,' he said breathlessly, 'and I think I know what happened! I'm willing to bet that this stuff was the final trigger for the collapse of the slope. We're on the verge of discovering the truth.'

'So you've found a substance that can do all kinds of shit,' said Peak, sounding unimpressed. 'Great. And where are the yrr?'

'The yrr-' Rubin stopped short. His self-assurance had evaporated. He glanced nervously at Johanson and Oliviera. 'Well…'

'Do you think these organisms are the yrr?' asked Crowe.

Johanson shook his head. 'No idea.'

For a while there was silence.

Crowe pursed her lips and drew on a cigarette. 'Well, we still haven't received a reply. What kind of organism would be able to respond? An intelligent being or maybe even a conglomerate of intelligent beings? What do you think, Sigur? Are those things in the tank intelligent?'

'You know perfectly well that it's pointless to speculate,' said Johanson.

'I just wanted to hear you say so.'

'How are we supposed to know if they're intelligent? What would an alien intelligence make of a bunch of human PoWs who can't do maths, and are moaning in a corner or sitting around apathetically because they're cold and scared?'

'Oh, God.' Vanderbilt groaned. 'Next thing he'll be throwing the book at us for infringing the Geneva Convention.'

'I didn't realise it applied to aliens.' Peak grinned.

Oliviera shot him a look of contempt. 'We're going to start running tests on the substance in the tank,' she said. 'Leon, tell me again what you saw on your solo recce in the docks.'

'Just before they fished me out? A blue glow.'

'You see,' said Oliviera, turning to face Li. 'You insisted on the military taking charge of everything, but your guys prodded around the Barrier Queen for weeks without any progress. They must have missed something crucial when they examined the water samples from the dock. Didn't anyone notice the glow? Or that there were single-cell organisms in the water?'

'We tested the water,' said Li.

'And?'

'Nothing. Ordinary seawater.'

'OK.' Oliviera sighed. 'Could I have another copy of the report, then? Including all of the lab results.'

'Of course.'

'Dr Johanson.' Shankar raised his hand. 'Do you have any explanation as to how they join together, what makes them do it?'

'How would they manage to co-ordinate it?' It was the first time that Roscovitz had spoken. 'How the hell does that work? And what's the point? It's like one of those cells is saying, "Hey, guys, over here, we're having a party!"

'Not necessarily,' Vanderbilt pointed out. 'The cells in our body make a pretty good job of co-operation, and no one tells them what to do.'

'Aren't you confusing that with the CIA?' There was a smile on Li's lips.

'Watch it, Suzie Wong.'

'OK, guys,' said Roscovitz helplessly. 'I just drive subs for a living. I need help. Human cells stick together just fine, but that's different- we don't dissolve whenever we feel like it. And, besides, we've got a nervous system to keep us in check.'

'The cells in our bodies communicate via chemical signals,' said Delaware.

'But what does that mean? Are you saying we're like a shoal with everything going the same way, doing the same thing, at exactly the same time?'

'Shoals only appear to move simultaneously,' explained Rubin. 'Shoaling behaviour is related to pressure.'

'I know that, for Chrissakes – I was only trying to-'

'Lateral line organs are located on the sides of the body,' Rubin continued undeterred. 'If a fish changes its position, it sends a pressure wave through the water. That wave is picked up by all the neighbouring fish, who realign their bodies until the shoal has corrected its position.'

'I know!'

'But of course!' Delaware's face lit up. 'That must be it!'

'What?'

'Pressure waves. If you had enough of these jellies, you could redirect a shoal. We kept asking ourselves what kind of spell had been cast on the fish to stop them swimming into nets – well, that could be the answer.'

'Redirect a shoal?' Shankar sounded doubtful.

'She's right,' Greywolf chimed in. 'If the yrr can steer millions of crabs on land and transport billions of worms to the continental shelves, you can bet they're capable of redirecting shoals. And that's easy with pressure waves. The shoal's sensitivity to pressure is practically the only thing that keeps it safe.'