Judging by their postures none of these people had been trying to get to safety. Chiku doubted that there had been more than a couple of seconds of awareness before the air roared out. Unconsciousness would have followed very swiftly, followed by death. She doubted that there had been time for fear.

  Just surprise.

  Chiku and Namboze tagged the bodies’ locations. Dedicated medical teams would arrive in time to preserve the corpses in vacuum with immense and loving care. Non-invasive methods would be used to assess neural damage. If there was even the slightest possibility of resurrection, the bodies would be shipped downstream to one of the holoships with sufficiently advanced medical techniques to carry out the process.

  They tagged the airlock as they exited and moved on.

  Their route to the next building brought them fearfully close to the wound in the world. A block ahead, the thoroughfare and its lines of flanking research buildings simply ended. The ground wrenched down, cracked and fissured, arcing and steepening to vertical. The wound was circular, maybe four hundred metres across. They climbed a ramp to get a better view, and looked right down into a circle of stars and blackness.

  Shafts and tunnels and service ducts threaded Zanzibar’s skin. They glowed in different colours on the overlay, coded for function and annotated for age, origin and destination. Many were disused or mothballed. Some were still weeping air or fluid – white or ghost-blue secretions cataracting into darkness. A tiny, trifling amount compared to the total resource load of the holoship, but it pained Chiku as much as the sight of her own blood would have.

  Crucible was still a very long way off.

  ‘What was here?’ Namboze asked, indicating the missing terrain with a sweep of her lit-up arm.

  Chiku knew. She had already consulted the suit’s map. ‘Various things. But the main one was Travertine’s physics lab.’

  ‘Are you sure?’

  ‘I wouldn’t have said it otherwise.’

  Namboze was uncowed by Chiku’s testy tone. ‘The explosion, whatever it was, must have started down in that bedrock, don’t you think?’

  ‘What makes you say that?’

  ‘There’d be a lot more damage to the surface structures, if it had begun above ground.’

  Namboze’s conclusion matched Chiku’s, but that didn’t make her like it any better.

  ‘We’ll leave the explanation to the specialists, Gonithi,’ she said firmly. ‘Our job’s to look for survivors.’

  She was glad that their search assignment took them no closer to the edge. They located and searched another building a few blocks from the first, standing on its own in what would have been an area of gently stepped wooded parkland, had most of the trees not been plucked from the ground. The building’s peeled-back roof had allowed atmosphere to vent from most of its levels, and they found no survivors on any of the airless floors. The basement – which had maintained pressure despite the loss of the roof – contained only a mindless floor-scrubbing machine still going about its duties.

  The day had already brought more bodies, more evidence of human mortality, than Chiku had confronted in her entire life. But on some numb level she knew they had been lucky. Many of Kappa’s laboratories and research facilities required only a skeleton staff. Some of them, judging by the reports coming in from the other search parties, had been running on a purely automated basis. Experiments in plant nutrition, soil hydration and so on, once established, could be set to run unsupervised.

  Yet the scale of destruction here was still almost unthinkable, and the loss of life might tally in the high hundreds or even low thousands once all the buildings had been searched. By any measure, this was a tragedy. But it could have been so much worse, had it happened in one of the densely populated chambers. Tens of thousands, easily. A civic catastrophe to equal almost anything that had happened since departure.

  So they had been fortunate. But it was something in Kappa that had made this happen in the first place. And Travertine’s research complex had been precisely at the epicentre.

  Chiku felt a coiled apprehension deep inside her. She knew this was not going to end well.

  For any of them.

  ‘Where’s the next structure?’ Namboze asked.

  ‘Over that way,’ she said. ‘Those two linked domes. I’d best check in with the coordinators, though – we’re already a little behind schedule, so they may decide to pull us back in before we get too tired.’

  ‘It’s an emergency, Representative Akinya – won’t they be expecting us to show some initiative?’

  Privately Chiku agreed. According to the schematic, they were looking at one of the oldest structures in Kappa, dating all the way back to the years before departure. Two domes, linked together – she thought of the soap bubbles that Mposi and Ndege liked to make. From their present angle, it appeared that the building had sustained damage to only one of the two domes, where a piece of the chamber’s ceiling had dropped onto it, cracking it like an eggshell. There would be airtight doors inside it, if the building was as old as the schematic claimed – they were a common feature in the older buildings, constructed when there was still a strong psychological need to defend against cavern blowout. In recent years, codes had been relaxed. The newer buildings rehearsed the architectural principles that would make sense on Crucible, rather than within a hollowed-out rock light-years from any sun.

  They found a door and cycled through. There was pressure on the other side, at seven-tenths of normal atmospheric. Chiku studied the reading carefully, until it was beyond doubt that the air was slowly draining away. A rough calculation told her that the building would not be capable of supporting life for much more than twenty minutes.

  ‘Seems unlikely that there are going to be survivors,’ she said, ‘but we’ll look anyway. The air pressure’s dropping quickly, though, so we’ll need to be quick about it.’

  ‘Can I make a suggestion, Chiku?’

  ‘Of course, Gonithi.’

  ‘It’ll be much quicker if we search different areas. Our suits will remain in contact, so we’ll know if either of us runs into trouble. We’ll be able to get to each other quickly enough if there’s a problem.’

  ‘I’m not sure we should split up.’

  ‘I’ll be careful.’

  Debating the point further would only waste more precious time, so they quickly agreed on a division of effort: Namboze would search the upper levels of the intact dome, Chiku the lower levels.

  The building was very obviously another laboratory, and although the aug remained mute as to its precise function, they had clearly been conducting some kind of physics or chemistry experiments. The high-ceilinged rooms were full of hulking, kettle-shaped machines, fed with pipes and conduits of impressive thickness. With the right queries, Chiku’s suit could probably have dug out the relevant information, but she did not need to know for her current purposes. Even in fundamental physics, there were few avenues of research that came anywhere near those prohibited by the Pemba Accord.

  Besides, this was not where the trouble had begun.

  She completed her search of the lower levels without incident. There were no survivors, nor any bodies. She checked her suit readings. Air pressure was now nudging below forty per cent.

  ‘I’ve found someone,’ Namboze said, grunting as she shifted position. ‘Still alive, but barely conscious. I’m going to get them into the portable preserver.’ Her voice was husky, on the edge of breathlessness.

  ‘I’ll be with you in a moment,’ Chiku said.

  ‘It’s all right – I’ve got it under control. We could use another party to help us ferry the survivor back out through the chamber, though.’ Namboze paused, her breathing heavy. ‘Once this one’s stabilised, I’ll complete my search of the upper floors. We missed this one’s life-signs – maybe there are more survivors.’

  ‘I’ll call for help. Don’t take any risks, Gonithi – you’ve done well as it is.’

  ‘Did you find anyone?’

>   ‘Empty down here so far. Pressure’s still falling, though, so pretty soon it won’t matter who we find. I’m going to take a look in the other dome, just in case there’s an air pocket. Call me if you find any more survivors.’

  The map showed Chiku a ground-floor entry point into the secondary dome, protected by a sturdy internal airlock of antique but foolproof design. The lock admitted her. Beyond was hard vacuum. She shone her light around, trying to make sense of mangled architecture. The ceiling fragment had daggered its way to the ground, crushing and buckling interior floors and partitions, and come to rest at a sharp angle. She moved around it cautiously, not sure how firmly it was embedded. Judging by the absence of machines and equipment, this part of the complex had likely been reserved for administration and supervision. There were chairs and tables, bent and squashed beyond easy recognition. A small refectory, unoccupied at the time of the accident. No survivors or bodies anywhere, as far as she could tell.

  ‘How are you doing, Gonithi?’

  The other woman sounded much more confident now. ‘Got the survivor bagged and stable. I’ve tagged the location and am completing my search. What about you?’

  ‘I don’t think there’s anyone here, but I want to make absolutely sure before we tag it as searched.’

  Chiku had swept the basement of the other dome, but it had not connected through to this one. She could see into the lower level at the point where the ceiling fragment had penetrated the floor. A staircase existed, but it was now buried under the rubble of the dome’s collapsed roof. The ceiling fragment itself offered a kind of makeshift ramp, if she dared trust it not to shift or collapse. The quilt of illumination elements studding the panel’s uppermost face – it had flipped over at some point after falling from the ceiling – promised enough traction to enable her to climb or scramble down.

  Chiku moved to the edge of the gap in the floor and stood with her toes on the very brink. It was four, maybe five metres down to a scree of rubble piled up on the basement’s floor. To reach the steep slope of the ceiling fragment, she would have to leap across a good metre of clear space, and then hope that she maintained her footing. Hesitating, she bent down and scooped up a chunk of debris as large as her helmet. She hurled it at the ceiling fragment, the suit amplifying the power of her swing. The chunk shattered in a silent eruption, blooming into a blue-grey cloud. The fragment had absorbed the impact without a hint of movement. It appeared to be solidly fixed.

  Chiku took a couple of paces back, then leapt across the threshold. She landed roughly, one foot slipping into empty space, but her other found a purchase. She grabbed hold of a pair of lighting elements and stabilised herself. The jump would not have fazed even Ndege or Mposi under normal circumstances, but she was alone, in a dangerous place, with only a spacesuit between her and vacuum, and for a few moments her heart surged on a rush of adrenalin and relief.

  Chiku descended carefully, spidering down the quilt of lighting elements until her feet touched debris. The ground crunched, then supported her. She stepped gingerly off the ramp and turned around slowly, sweeping the beam over the jumbled and unwelcoming surroundings. Even the dust kicked up as she moved curtained back down with indecent haste.

  ‘Chiku,’ came Namboze’s voice. ‘I’m done here. There’s no one else alive so I’m heading outside. I think I can manage the preserver on my own.’

  ‘Good work,’ Chiku said. ‘I’ll be with you in a few minutes.’

  Leaning around a buckled metal pillar, she took cautious steps deeper into the basement. It had been subdivided into two large rooms, but the intervening wall had collapsed when the ceiling fragment came down. She stepped over and around chunks of knee-high rubble, watching where she placed her feet.

  Namboze asked, ‘Where are you?’

  ‘Just completing a sweep of the secondary basement. It’s open to vacuum, but I wanted to be sure. Doesn’t look like there’s anything down here, though.’

  Chiku fell silent, heart jamming her throat. She had been about to put her foot down into what looked at first glance to be a shadowy space between two chunks of debris. An instant before committing herself, she realised it was a void, not shadow.

  There was a hole in the floor.

  Namboze must have heard her draw breath. ‘Chiku?’

  ‘Still here. Nearly lost my balance.’

  Chiku steadied herself. She poked at one of the boulders on the edge of the void. It teetered and fell in, increasing the diameter of the void. It had been big enough to swallow her foot to begin with. Now it was big enough to swallow Chiku.

  If the boulder landed on anything below, it did so without a hint of impact. She found the void troubling in a way that felt monstrously disproportionate to its size. According to the aug, no sub-levels or infrastructure pipes lay beneath this laboratory, even allowing for decades of disuse or abandonment. The overlay had proven accurate so far.

  Chiku was greatly unnerved by this sudden discrepancy. Zanzibar’s memory was as limitless and infallible as a person’s was cramped and unreliable. Zanzibar was meant to know every wrinkle and pore of itself.

  But it did not know about this hole.

  Chiku took another deep, steadying breath. What was more likely: that a hole had been present where none was charted; or that the accident, the violence of the collapsing ceiling, had shifted the structural foundations beneath the laboratory and revealed the opening? This rift could only have opened up today, when Kappa blew out. Given the scale of destruction Chiku had already witnessed – that four-hundred-metre-wide hole punched clean through Zanzibar’s skin to space – a lack of additional structural shifts elsewhere within the chamber would have been more remarkable than finding this one.

  But then she risked leaning far enough over the edge to allow her helmet light to spill into the void, and saw that whatever this might have been, it was not another rift.

  This hole was the entrance to a shaft, and the shaft’s walls were not only smoothly bored but set with recessed handholds. It curved away beneath her, out of sight and into darkness. And Chiku shivered, because such a thing had no business existing on Zanzibar.

  A secret passage.

  She looked around and her gaze chanced upon a sheet of lightweight walling material that must have come loose when the overlying floor collapsed. Moving carefully – what little faith she had had in the integrity of the floor beneath her had vanished the moment she found the void – Chiku grasped the blade-shaped fragment and levered it free. She positioned the fragment over the hole, adjusting it until she was satisfied that she had concealed her discovery as best she could. The hole’s dark mouth was still visible under the fragment’s edges, but to the unsuspecting eye it looked like shadow.

  There was no need to tag the location.

  CHAPTER SIX

  From the transit station, all the way up the winding stone-walled paths to her dwelling, Chiku ran a gauntlet of questions from well-meaning citizens. They had learned from Noah about her visit to Kappa and they wanted to know what she had seen inside. Most of all, they wanted reassurance. Chair Utomi might have told everyone that Zanzibar was safe, but what else could he say? Chiku had first-hand information and they were eager for it. She did not have to lie to them, or bend the truth to any excessive degree, to give them what they wanted. Things will be all right, she assured them. It’s bad, but we’ll weather it. We have the local caravan to call on. There will be no more deaths.

  Eventually she had to start telling them not to ask any more questions, that she had already told them all she knew. She directed the rest back down the path, to the people who had already interrogated her. Talk to them, they know the picture.

  When she finally reached the house, she was surprised to see Noah sitting outside it, squatting on one of the low walls. Mposi and Ndegi were at his feet, squabbling over a game of marbles. Noah had an odd look about him – not the relief and concern she had been counting on.

  ‘I’m glad you’re safe,’ he said, rising
from the wall.

  She had expected to find him indoors, preparing a meal, not daydreaming out here. ‘Yes, I’m safe,’ she said guardedly. ‘Is everything all right?’

  ‘I’m not sure.’ Noah embraced her briefly, breaking contact almost as soon as he had initiated it. ‘We have . . . well, it’s difficult to explain. I think you need to go inside.’

  ‘Why are you waiting out here?’

  ‘I think you need to go inside,’ Noah repeated, as if she had not heard him the first time. ‘I’ll wait here with the children. You can decide what we should do next.’

  This was definitely more strangeness than she needed at the end of a hard day. But Noah was a good husband and not given to dramas. She nodded wordlessly, knelt down to kiss the children – tousled their hair, whispered that they should play nicely. And then – steeling herself – she entered the house.

  Travertine was sitting at the kitchen table, hands before ver, fingering a wine glass.

  ‘Hello, Chiku.’

  Chiku said nothing at first. Travertine had poured the wine from the same bottle she and Noah had started the evening before their mission to Malabar. Chiku eased into the seat opposite Travertine and helped herself to a sip from the same glass. Then the sip became a gulp, and she carried on drinking until the glass was empty and her throat was burning.

  She said: ‘You shouldn’t be here.’

  ‘In the immediate sense, or the existential?’

  ‘Dead, alive, whatever – you shouldn’t be in my house. Not after whatever happened today.’

  ‘I have no idea what happened today.’

  ‘Whatever went wrong, it started with your laboratory. You did this. You did this and they’re going to hang you for it.’