No more than thirty light-years from here, Ty reflected. How easily the words tripped off Cesar's tongue. They'd travelled a thousand light-years without any help from the Shoal, putting them on a par with the greatest explorers the human race had ever known.

'How could they get here so soon?' he demanded. 'I thought the best estimates gave us at least another month before they arrived here.'

'Nathan… Cesar… for Christ's sake, shut up and get packing, will you?'

Ty turned his attention to Nancy. 'Look, we can't possibly leave here with nothing to show, not after coming all this way. Tell me exactly how much time you think we have left, to the precise minute if it's at all possible.'

He could just make out her terse expression through the visor. 'Nathan-'

'Just humour me, okay?'

Nancy hesitated, and Cesar jumped in. 'I'd say anything from ten to twenty-four hours before they're right on our doorstep, Nathan. But I don't rate our chances of survival very high if we aren't ready to jump out of here before then.'

Ty thought hard for a moment. 'Okay, but once the swarm does reach this system, exactly how long do you think we have before they pinpoint our exact location?'

'Nathan,' Nancy spoke as if she were talking to a slightly dim child, 'if there was ever anything here, it's long gone now. Give it up.'

'Is that Martinez's opinion too?' he countered.

'Of course it is, otherwise we wouldn't be packing up, would we? Unless you've got any last-minute bright ideas.'

'Maybe I do. Look, we spent a week just trying to find this rock after we arrived in this system, right?'

'What's your point?' asked Cesar.

'The swarm needs to find us first, or more specifically this one asteroid out of the huge volume of them surrounding the white dwarf. Now, clade-worlds are always found within specific distances from their stars, which is one reason we managed to find this one as quickly as we did. The swarm's going to know that, but it still means we're going to have at least some time to finish our work before they trace us.'

'We really don't have time to debate this,' Nancy snapped, her voice getting louder. 'You've worked harder than anyone else, Nathan, and there's no reason we couldn't come back here some other time and try looking again, after the swarm is gone.'

'Think about what's at stake,' Ty insisted. 'What's going to happen if we return empty-handed?'

'Jesus and Buddha, Nathan!' Nancy finally exploded. 'Don't you understand? All that happens if we stay on now is we get killed, and it's all over either way! Not unless you finally think you found the damn…' She stuttered to a halt, and he realized she could see the grin almost splitting his face in half.

Cesar looked back and forth between them. 'What – you found something?'

'There's an anomaly,' Ty explained. 'It was right there in front of me the whole time.'

'So why the hell didn't you mention it before?' Nancy demanded, angry again.

Ty shrugged, then remembered the gesture probably wouldn't be visible to the others, regardless of how light and flexible their suits were. 'You didn't really give me a chance. I came up here when you called, and-'

'Okay,' Nancy said, cutting him off. 'Okay, what anomaly?'

'I'll need to show you,' he replied. Nancy conferred quickly with Martinez and got permission for them to go back inside the asteroid. Cesar remained on the surface to supervise the spiders as they busily manoeuvred the packed tents and supplies on board an unmanned cargo transport that had just arrived from the frigate.

'I hope you know I'm risking my life for you,' Nancy muttered over a private channel, her voice tense.

'I promise I won't read too much into it,' Ty replied. The shaft walls slid past as they dropped down into darkness, each of them carried by a spider-mech. 'God forbid you might ever admit to actually liking me.'

'It's not that I don't like you; it's just that… I don't know.'

'"I'm just not your usual type." That's what you always say, isn't it?' he asked.

Sudden, intense sexual relationships were to be expected, while so far from home for months at a time; and such had been part and parcel of Ty's experiences while exploring other clade-worlds in years long gone by. But he never let himself forget that Nancy Schiller was a Freeholder. She was not unlike Karen, in that she was used to a life of discipline, and her body was a landscape of smooth, well-trained muscles; whenever they shared a bed, Ty would find himself wondering whether life under an assumed identity had left him with a perverse attraction to the threat of discovery.

He heard her sigh, over the channel. 'Forget I said anything,' she muttered. 'How long before we get to this chamber?'

'Not long. Does it matter?'

'No,' she grumbled. 'It's just…'

'What?'

She made an irritated sound. 'I just can't stand to think of those… machines hunting us through all this darkness.'

'It's not far,' he replied, knowing she was referring to the images of swarm-components they'd occasionally watched since departing Ocean's Deep.

The mouth of the shaft had shrunk to almost nothing, and now the only light came from the spider-mechs' lamps, which cast sharp-edged pools of illumination against the walls of the shaft as they rushed by. Their conversation lapsed into silence, and Ty guessed Nancy was just as intimidated by the scale of the clade-world as most people were the first time they found themselves inside one.

Before long they reached the crossroads at the asteroid's heart. Someone had directed a spider to nail up a handwritten sign indicating basic directions. Ty braked, and waited for Nancy to do the same.

'We're going into Chamber Two,' he explained, nodding in the direction of Shaft B West. 'It's pressurized, okay? That means we can-'

'Nathan, I know you're dedicated to your work, but get your head out of your ass. Remember I'm the one who writes the daily progress reports. What makes you think I don't already know it's pressurized?'

'Sorry I was just thinking out loud. Another hundred metres, then down the hatch.'

The Atn usually left a basic assortment of data and tools behind whenever they abandoned a clade-world, but in this case there seemed to be a surfeit of artefacts both physical and virtual. The data was recorded on storage devices built around a core of self-repairing molecular circuitry, the resulting stacks resembling rows of bronzed shields embedded in the walls of dedicated chambers. Most, but not all of the data stored there still remained incomprehensible to human researchers.

The stack chamber was accessed through a pressure seal installed by spider-mechs shortly after their arrival. They passed through the airlock quickly, Ty pulling off his helmet once they were inside the chamber. He watched as Nancy did the same, shaking sweat from frizzy blond hair cut into a bob.

The chamber was rectangular, its walls crowded with the ubiquitous spiral-form glyphs. A heap of what might appear to the casual observer as nothing more than blackened junk lay jumbled in one corner. The remains of eight Atn stack-discs were embedded in the wall directly opposite the pressure seal. Each had been carefully and deliberately vandalized; fragments and chunks of the discs lay scattered all around.

Nancy knelt by the pile of junk and poked at it with one gloved finger. 'I don't know, Nathan, we've already been over every inch of this place, and I'll be seriously surprised if we've missed anything.'

Ty pulled off a glove and ran one hand over the ruined edge of a stack-disc. 'We missed one thing.' He nodded towards the pile of junk in the corner. 'That's the remains of an Atn, for a start.'

'Oh.' She stood up and took a step back. 'Are you sure?'

He glanced past her at the twisted remains, which were hardly recognizable as having ever been anything living. 'I ran a tomographic analysis on some trace organic remnants. It's definitely the remains of an Atn, and it's been subjected to extremely intense levels of heat, like something turned the interior of this chamber into a furnace. You remember what Cesar found out about those craters?'