And there was movement on that complex surface, chains of bright lights, crawling like the trails of some exotic insect.

  Ulla saw glints of metal. A mechanised world.

  She was dazzled by all this, flinched at the brilliance – she couldn’t help it.

  Pulet grinned at her reaction.

  Mott, by comparison, just stared at the screen, eyes narrowed.

  ‘So,’ Pulet said at last, without preamble, ‘this is a planet of a kind we call a Mercury. Like Mars, Earth, the labels you use also, these names must be derived from the language of our common ancestors. Common referents. Once there was only one Mercury, or only one known one of that type – a rocky world close to the Sun – an example which has bequeathed us a model, a label, a name. A type in the classification of worlds …’

  Ulla shared a glance with Mott. Yes, we know, he always talks too much. Humour him.

  ‘But what we are building on this Mercury …’

  The viewpoint sailed towards the horizon once more, to reveal more of those obviously artificial workings: scars in the surface with dead-straight edges, and apparently smooth, vertical walls plunging down into the thickness of the crust, for some depth. Some of these scars must be kilometres in length too, Ulla thought. This was a big facility. For building something just as large?

  As the viewpoint sailed close to one of these great worked scars, Ulla leaned forward, strained to see. Was there a structure in there, perhaps, lying in that immense trench? Not a cylinder, but a great rectangular slab of engineering, its upper surface encrusted with fittings. Fittings. What looked like lightsail mounts. Huge drums as if for sail cables, and indeed what looked like collapsed sails, but enormous …

  Ulla murmured to Mott, ‘If those things are vessels they’re far larger than anything we’ve seen so far. Even compared to the Hierarchy’s existing, vast sail warships …’

  But the commodore just touched her fingers to her lips, and pointed to the protector.

  Who resumed his lecture in a low, rapid mumble. Talking again about the planet below.

  ‘Mercury 43, then,’ the protector said.

  ‘Basically classified by its size, to some extent location. But,’ he went on, ‘I think it’s fair to say that worlds like this, the Mercury group of Hearth worlds, are generally defined by their nature, their content – mineral-rich – rather than their position in the sky.

  ‘We know that planets are baked in the collapse of interstellar clouds. Worlds far from the cloud centre, cool, can collect huge volumes of gases, liquids, ices, perhaps around a rocky core. Neptunes. Worlds that congeal near the centre lose all their volatiles, or almost all, and the result is an agglomeration of dust, of rock. In extreme cases, Mercurys, as you see here. Intermediate worlds like Earth can keep a metallic core, mantles of silicon, as well as volatiles in liquid form – water, for example – or perhaps in the form of ice.

  ‘In many stellar systems, few planets migrate any great distance from where they formed. The gas and ice giants remain far from the star itself, and the small, rocky, volatile-free close to the star. But in Hearthspace such planets can migrate far from their place of origin. Giant planets pull each other around, they go swooping down into the clusters of minor planets closer to the Hearth – and push them around the sky, to a far greater extent than in a stellar system like the system of Earth.

  ‘And so here we have found a cold Mercury, as you can see. Like an Earth stripped of its upper layers, all its volatiles, leaving a core of rock and iron. And, without a casing of water and air, is easily mined.

  ‘And, as you can surely see too, we have made of this world a cradle for one of our greatest technological achievements. One which,’ he said, looking intently at them, ‘will transform the human Hearthspace, drastically and permanently. Both inner and outer worlds, joined by multiple flows, flows of resources, goods – and, crucially, people. A union of our sundered race, unparalleled since the scattering that seems to have occurred at the arrival of humanity in Hearthspace.’

  Mott looked up defiantly. ‘I do wish you’d get to the point for once, Protector. Where are you going with this? What exactly are you building here? What’s it for?’

  But Ulla saw it. ‘It’s a shipyard. A shipyard in the sky. On a huge scale. He’s building a huge ship.’

  Pulet grinned.

  And Mott and Ulla exchanged wary glances.

  ‘Let’s discuss our super-Mercury again – and what can be done with it,’ Pulet said.

  ‘As I pointed out, on such a world we are at least not having to bother with an outer clutter of volatiles, of oceans and atmospheres and living things.

  ‘And on such a world as this, the materials from which it’s made sort themselves out, as if waiting for our mining machines. It’s all heat and gravity, competing, along with a little chemistry. Essentially the iron sinks; the silicates, lighter, less dense, rise up.’

  Ulla nodded. ‘So the iron congregates in the centre—’

  ‘Yes. The detail depends on the size of the planet, but you can get a solid iron core – solid because of the pressure of the upper layers – and, lingering, a liquid iron layer around that. Above that a silicate layer – the deeper stuff still hot enough to flow – like lava, if you know the term. And above that a solid crust – as the rocky stuff, tens of kilometres of it perhaps, cools to hardness.’

  Mott nodded her head. ‘Very useful. So, to progress your big engineering project, you can land in safety on that solid crust, set up your mining operation, dig your way down to liquid iron you can just pump up …’

  Pulet nodded, smiled. ‘I knew you would enjoy hearing about this, learning more. It’s a tragedy that we find ourselves at war—’

  Mott snorted. ‘You started it.’

  The guard, who had been standing attentively for a long time, Ulla realised, now put a hand on the knife at her waist, and took one step forward.

  But Pulet waved her back, languidly. ‘Here at least we can speak freely, and honestly, that’s all. So refreshing, don’t you think? So sad we find ourselves on opposite sides of an unnecessary conflict. For surely our overriding goal is one we share, to propagate humankind across this Hearthspace, across this marvellous, fecund cloud of worlds.’ He sighed. ‘But what a shame we have to wade through this fog of deception, of hostility. When we are capable of greatness. All of us.’

  Ulla found herself shivering.

  Mott was calmer, but seemed to pick up on that word. ‘Greatness, Protector.’ She gestured at the screen. ‘What greatness is this?’

  Pulet smiled. ‘I have more up-to-date images. Of what we are building, here on this Mercury clone.’

  He swiped through images, hanging in the air, until he found what he wanted.

  Mott and Ulla exchanged glances.

  Then leaned forward to see.

  They were looking down, now, on the surface of this rogue Mercury – closer to its silicate rock surface. And in the region they inspected, a wide swathe of that surface was disturbed, Ulla saw, centred on a pit, longer than it was wide, crowded with machines, surrounded by mounds of what looked like spoil and supply heaps. This location seemed to be the hub of significant activity, with a number of shelters around it, and roads of some kind laid across the rocky surface, leading towards it.

  And, lying in the long pit, the centre of the activity, was what looked like a vessel: a broad cylindrical body, with a wider upper storey. All this was encased in scaffolding and shadows, but the Hearthlight was bright enough for Ulla to make out much of the detail. At the prow, anchors for lightsail lines, she thought.

  Evidently a lightsail ship – much larger than the bolt-ship, and it certainly didn’t fit that classic bolt-ship profile – but sail ship it was.

  Much, much larger.

  And on the upper deck, small figures. Like humans, lying flat, inert.

  Hundreds of them, more, loosely stacked. All too uniform to be genuine corpses, surely. Dummies, then, used for the purpose of testing the design.

  Dummies. She hoped.

  Ulla glanced around.

  For once Pulet didn’t appear to be gloating over his latest display. He seemed – quietly proud.

  But Commodore Mott seemed agitated. In the face of this hot world, coldly angry.

  Mott pointed. ‘Look at the scale, Breen.’ She leaned forward. ‘Look – look at these small figures. Humans. Those are humans. Look at the scale.’

  ‘Just test dummies for now,’ Pulet said. ‘The only live humans down there now are construction workers – some enslaved, all skilled to some degree. But, yes, they are dummies, for now, human-sized—’

  Mott glared at Pulet. ‘And it is clear that many humans can be transported in such ships. This is a dedicated slave transporter, isn’t it? Orders of magnitude larger than this scrubby bolt-ship …’

  Pulet smiled. His pride seemed obvious. ‘We call this design simply the Mass Transport. Modest, and apt, don’t you think? The main body is about four hundred metres long,’ he said. ‘You can see—’

  ‘Four hundred metres,’ Mott said. ‘What, eight times the length of this bolt-ship? It would take some time just to walk the length of the thing.’ She glared at the protector. ‘How many? How many slaves on board? I mean, if this bolt-ship carries fifty people or less—’

  ‘Maximum capacity seven hundred thousand articles,’ Pulet said. He actually grinned at that number. ‘They can’t be accommodated in the comfort afforded by this sturdy little vessel, of course. The freedom we give you! Not any more.’ He laughed. ‘I do find myself – inspired by this marvel of technology. It’s all very new, you know. Developed since we became aware of your crowded worlds, your crowded populations. And here is our solution as to how to manage those populations.’

  ‘“Manage those populations”,’ Mott asked coldly. ‘Seven hundred thousand, three quarters of a million, in a single cargo. Is that what you’re suggesting?’

  Pulet said, ‘Of course there are qualitative differences in the design compared to lesser transporters. Aboard this ship, immobilisation is necessary. Shackles are permanent. Imagine it – rows of slaves, tiers of them stacked high. But there are measures to ensure health. Daily rotation for instance, to stop the blood pooling.’ He grinned. ‘As if the cargo are on spits, rotating on their long axis. And so forth.

  ‘And here’s the design strategy. Rather than have our slaves as passengers, effectively, and labouring over an external life-support system – external to their bodies at least – here we have the slaves locked into the support system. Permanently attached, with feeding tubes and waste extraction. Their whole bodies as components of a single machine, humanity and blue-green algae as mutual symbiotes serving a single, optimised recycling system.’ He grinned. ‘Can you see the elegance of the design? There would be regular sluicing. The dead are removed, of course, but simulations show that the losses are comparatively small. Economical. And even those who die are fed back into the life-support systems, to feed the survivors.

  And that is how we can achieve such compact loading. A whole city’s worth of slave labour, transported across a hundred thousand astronomical units in a single passage. Can you imagine it? And can you imagine the boost to our industrial capacity across the Hearthspace, with the capability to transfer such deep stacks of human components, across Hearthspace, across Alliance space, and even your own cold worlds – all integrated into these tremendous flows of assets – raw materials, slaves, finished products! … Imagine it!’

  And Ulla could imagine it. To be racked up, immobilised, stacked up like slabs of meat with nearly three-quarters of a million others … To be a cargo item … a component in a huge, closed life-support system …

  ‘Crowds of humans themselves like blue-green algae in a recycler tank,’ she murmured.

  ‘Exactly.’ Pulet seemed delighted at the insight, the comparison. ‘Well. You can see how it works. Quite effective, efficient.’

  Ulla, horrified, tried to find some crumb of comfort. ‘But the slaves – are they kept sedated?’

  ‘Oh, no, why do that? Consider the cost alone. No, they will remain conscious – although we expect a regular sleep cycle to be maintained once a period of adaptation has passed. There will be stimulants, electrical manipulation of muscles, to maintain overall health.’

  ‘A “period of adaptation” – adaptation to this? And – and children? Babies?’

  ‘There will be no procreation during the voyage, of course. Well, save among the crew, and we can’t legislate against that.’

  Pulet actually laughed at that, astonishing Ulla.

  Mott seemed furious. Apparently finding it difficult to speak.

  ‘You know, I think I should have anticipated this development. Your deadly mixture of callousness and high technology. My imagination – has failed me. Of course you would build such ships, if you could. For you aren’t content with random raids on our home worlds. Picking up a few hundred, even a few thousand. You would empty cities. Worlds. Take away their populations, with people stacked like slabs of meat. And conscious all the way.’

  ‘Indeed.’ Pulet smiled again. ‘Also, by the way, with alternate engineering this marvel would be a battleship of significant capacity. A war machine in a single vessel.

  ‘This is a mere prototype. Even this, however, would suffice to mount a successful attack on any of your feeble worlds – and then to retrieve whole populations the size of cities in single missions. Retrieve them to pursue better lives, if shorter, in the service of the Hierarchy.

  ‘Thus, the future. We will build a fleet of these ships – or rather, you will, for us. All very efficient.’

  And Mott said, ‘I pledge that I will destroy that monstrosity, or die trying.’

  Pulet grinned. ‘Good luck!’

  That was when the general alarm sounded.

  38

  The room’s door slammed shut, making an airtight seal, Ulla knew.

  The guard on duty immediately stepped forward, moving between the protector and Mott and Ulla. Somehow she had her weapon, a blade, in her hand, Ulla noticed in that first heartbeat.

  ‘Don’t move. Don’t stir. You too, Protector, sir. Don’t so much as—’

  ‘We know,’ the commodore said. ‘We’re soldiers too, remember. You’ll have no trouble from us.’

  The guard just glared back. Stayed on alert. Doing her job scrupulously, Ulla thought. Good training, good soldiering. Not all of the inhabitants of this outer Hearthspace were idiots or callous cowards, she had to remember that. And no wonder then that Captain Erbas, no fool, had assigned this particular guard to nursemaid the protector, at this moment.

  The protector himself was sitting, frozen, as if utterly bewildered. As if he had no idea what was going on. As if he couldn’t even grasp the nature of this drama, conceptualise it. He made no effort to move, to question the guard, to access his systems.

  Ulla risked a glance at Mott. The commodore was all but expressionless. Just waiting.

  Ulla leaned over and said, ‘You know, I’ve spent so much time in this room—’

  Mott snorted. ‘Gazing out at the wonders of the Hearthspace with the protector at your side.’

  ‘Yes. And now I’m about to see – what?’

  ‘A war,’ Mott murmured. ‘If our comrades have anything to do with it.’

  At last the captain, Erbas, spoke, his voice and image carried through the slaver’s rarely used comms system. ‘Protector Pulet. Erbas here, on the flight deck. Stay where you are, sir. You are in your escape pod, if the worst comes to the worst.’

  Another glance shared with Mott. They were learning a little more about the nature and structure of this slave-ship all the time. So this fancy observation lounge doubled as an escape pod for the protector? It made sense that Pulet’s favourite playground was also his bolt-hole, Ulla thought.

  Mott raised one hand, just slightly. Just sit tight and wait on events. The obvious stratagem.

  Advice the protector didn’t follow.

  ‘By the Hearth itself, Erbas, tell me what’s going on! Why the general alarm? Are we under attack? Seriously? From who, how?’

  In response, the screens in Pulet’s lounge filled up with what looked, to Ulla, like summaries of tactical data.

  Erbas spoke again. ‘We’re pretty sure we know who, Protector. Ships of the same design, roughly speaking, as the small ship we overwhelmed back in Alliance space—’

  Ulla knew immediately what Erbas was talking about. The legacy of Fels Sedhi, test pilot of a prototype dark-matter ramscoop. Fels, whose hasty initiative to send out dark-matter ramjet drones to pursue the Hierarchy ship had enabled the Alliance authorities to track the invaders.

  Mott grinned. ‘That was an experimental test article. You may as well get the name right in your log, Captain Erbas. The pilot was a volunteer, called Fels Sedhi. If he didn’t survive – even if his career lasted only a few months, his one significant achievement took only hours – he kept the technology from you, and, who knows, might have swung this war before it even started—’

  That seemed to infuriate the protector. He clenched a fist, and made to get out of his chair, heading for the commodore.

  But his guard restrained him – physically, a hand on his shoulder, firm enough to keep him in his chair. ‘I wouldn’t do that, sir. We’re under control here, in this cabin at least, and I want it to stay that way.’

  Mott said now, ‘Your captain is wiser than you, Protector. Even your guard is. No wonder you’re going to lose this war.’

  She actually laughed at Pulet, though Ulla winced at that.

  ‘It’s not a war yet, Commodore,’ Erbas called, more calmly. ‘And I’ve a little more news for you, the crew of Patrol 45. Several of your ships have similarly conveniently identified themselves. Patrols numbers 52, 79, 84, 119. Survivors of a larger group, I’m told – I mean, most of these ships were downed without getting close to the capital worlds, let alone doing any damage … However the survivors have now converged on what they seem to have correctly identified as Hierarchy Prime, the planet cluster from which the Hierarchy is governed. Our defence squadrons are rising to meet them.’