26

Agata took hold of one end of the slab of calmstone, Ramiro the other, then they lifted it onto their shoulders and stood facing each other, some four strides apart.

“Are you ready?” Tarquinia asked.

“I’m not sure how steady this will be,” Agata replied.

“That doesn’t matter. I just want you to be able to keep your grip when there’s a force applied from below.”

Agata put a second hand on the slab. “All right. Go ahead.” The improvised test rig looked alarmingly amateurish, but the ceiling of the cabin was made of the wrong material, and in any case they didn’t want to leave it covered with incriminating marks. They’d hunted through the storeroom for something to serve as a trestle, but there’d been nothing ready-made, so in the end their bodies had seemed like the most expeditious substitute.

Tarquinia pushed a button on the remote control and the occulter rose from the floor. The core of the tiny craft was a dodecahedron about a span wide, with air nozzles fixed in the centers of eleven of its pentagonal faces. Attached to the top, twelfth face was a linear assembly, a pair of arms three or four spans long, as densely packed with gears and linkages as anything from the age of clockwork.

Staying low, the occulter steered its way across the cabin until it was hovering in front of Agata’s feet; she could feel the spill of air against her skin. Then it ascended smoothly until it made contact with the calmstone slab—surrogate for the slopes of the Peerless itself. She gripped the slab tightly as four burred tips drilled obliquely into the stone. As Tarquinia had promised, the net force was purely vertical, so the weight of the slab bore most of it, and with the drills counter-rotating in matched pairs Agata felt no torque trying to twist the slab sideways.

After a few lapses the drills fell silent and the air jets cut off, leaving the device hanging.

“Try to shake it loose,” Tarquinia suggested. Ramiro ignored the invitation, but Agata slid her end gently from side to side, and when this had no effect she grew bolder and began rocking the slab back and forth. The linkage rattled alarmingly, but the four splayed drill bits remained lodged in place.

“That’s reassuring, isn’t it?” she said. “The mountain is hardly going to sway like that.”

Ramiro wasn’t so impressed. “It doesn’t tell us much about the real hazards. If there’s a hole under the surface, or a powderstone inclusion—”

“If it comes loose that’s not the end of the world,” Tarquinia stressed. “It can always fly back and reattach itself.”

Agata said, “Try the walking mode.”

Tarquinia tapped the remote. The four bits remained fixed in the stone, but the plate on which the drills were mounted began rotating on the end of its arm—or rather, the arm began rotating around the plate, swinging the entire occulter forward, carrying it from Agata’s end of the slab toward Ramiro’s.

When this repositioning was complete, the four drills at the end of the second arm pushed up against the stone and began biting into it. The new quartet managed to gain purchase with only the first set bracing them; there was no need to start up the air jets again. Then the first four went into reverse and disengaged from the stone, and the whole process began to repeat itself.

Agata watched anxiously as the machine whirred and clanked its way down the slope from her shoulder to Ramiro’s. If the slab was unrealistically smooth, at least they’d made sure that it wasn’t gravitationally level.

When the occulter had come within a span of Ramiro’s body, Tarquinia used the remote again. The craft freed itself from the slab and flew away to alight on the cabin floor. Ramiro looked to Agata, and they carefully put the slab down together.

“Not bad,” Tarquinia declared.

Ramiro said, “No. But we still need to decide what happens when the surface is uneven.”

Tarquinia had already reached her position on that. “It should detour around the problem if it can, or drop away and fly past it if it can’t. That makes it purely a question of navigation.”

“And a question of air,” Ramiro corrected her.

“Whatever we do,” Tarquinia replied, “there’ll always be a chance of the air running out. Letting the arms tilt so they can conform to the surface won’t guarantee anything—and it’s one more joint that can jam, two more actuators that can leak, plus six more sensors to make the idea work at all.”

Ramiro turned to Agata. “It looks as if it’s your vote.”

“Can we model the air use for different scenarios?” she wondered. “Take a guess about the roughness of the mountainside, and see what the chances are that we can get these things from the dock to the antipode with air still in the tank, for each design?”

Ramiro said, “I can try, if you want to help me with the model. ‘Roughness’ isn’t the easiest thing to quantify, but you’re the expert on curvature.”

Agata sat beside him and they spent the next three bells working through the problem. In the end, with some plausible assumptions, there was a chance of about five in a gross that the current version of the occulter would run out of air before it had completed its task. With a new model where the arms could fold together or bend apart—allowing it to keep its grip in bumpier regions—that fell to three in a gross.

Ramiro said, “That’s for a single machine. But even if we build half a dozen spares, we can’t afford too many failures.”

Tarquinia had been doing calculations of her own. “You need to add in the chance of the modification itself leading to a failure. I get two in a gross for that.” Ramiro looked skeptical, but when he went through her numbers he couldn’t fault them.

“Five in a gross … versus five in a gross.” Agata couldn’t see how to break the tie. None of these numbers were precise, but without more information she couldn’t make the uncertainties any clearer.

She looked across the cabin at the occulter. Their encounter with the Hurtler and their bomb-removal project offered plausible excuses for all sorts of items ending up in the void, or lost in the dust of Esilio—but she was already afraid that their depleted stores might attract suspicion. Ramiro’s proposed changes would require dozens more proximity sensors—spares that ought to have been packed away neatly in a single large box. Why would they have taken that box out of the storeroom for safe-keeping, but then never brought it back?

“I’m voting with Tarquinia,” she said. “What we’ve got now is physically robust—and we’ll already be hard pressed to build and test the whole swarm before we arrive. This isn’t the time to start making things more complicated.”

For a moment Ramiro looked poised to respond with a further plea, but then he was silent.

Tarquinia said, “It’s good to have that settled. Everyone should get some sleep now, and tomorrow we’ll go into production.”

“Do you want some fresh pictures for your wall?” Azelio asked, offering Agata a sheaf of papers.

She took them from him. The first drawing showed the mountain coming into view through the window of the Surveyor, with Luisa and Lorenzo standing on the summit waving, very much not to scale. In the second, they’d thrown out a docking rope to the craft and were reeling it in by hand. “These are great,” she said. “Thank you.”

Azelio lingered in the doorway. “Come in for a while,” she suggested. He followed her into the cabin. There was only one chair, so she sat on the edge of the desk.

“I’m going mad,” Azelio said bluntly. “I don’t know what to think any more. I don’t know what to do.”

“And I don’t know what to tell you.” Agata had talked him through the situation a dozen times, but he was never satisfied with her account.

“Tell me that the mountain won’t be destroyed,” he pleaded. “Tell me that everyone will be safe.”

“The occulters aren’t looking too bad,” she said. “There are benign ways that the disruption might happen; I can promise you that.”

Azelio glanced down at the pile of notes on her desk. “And doesn’t everything that could happen, happen? Isn’t that what your diagram calculus says?”

“No.” Agata nodded at the pile. “For a start, you can only add up diagrams that begin and end in exactly the same way: they all take different paths, but their endpoints have to be identical. Getting to the disruption with benign sabotage leaves the mountain intact; getting there with a meteor strike hardly brings you to the same state. And even when the endpoints are identical, all the alternatives you draw for a process just help you find the probability that the process takes place. Those alternatives don’t all get to happen, themselves.”

“Then what makes the choice?” Azelio pressed her. “When a luxagen could end up in either of two places, how does just one get picked?”

“No one knows,” she confessed. “In the years after wave mechanics was developed, there was a big debate about whether it was truly random, or whether there was some hidden structure beneath the randomness where all the results were certain. For a while, one group of physicists claimed to have proved that there couldn’t be a deeper level. Their proof looked quite persuasive—until Leonia showed that it was tacitly assuming that information could never flow back in time.”

“Ah, the strange things people once believed,” Azelio observed dryly.

Agata said, “No one believed it, even then, but they found it easier than we do to forget that it wasn’t true.”

Azelio lifted a diagram from the stack. “So what can this tell us about the disruption?”

“Nothing.” Agata wasn’t sure how he’d ended up clutching at the diagram calculus as an answer to their plight, but if she’d been careless in describing her work to him in the past then what she owed him now was as much clarity as she could muster. “Just because we don’t know the cause of the disruption, that doesn’t mean that every cause we can imagine will coexist. If you want history to unfold a certain way, forget about wave mechanics. What matters now are the usual things: who we are, what we do, and a certain amount of dumb luck.”

Azelio put the diagram down. “So if there’s a meteor coming, how do I stop it? Or avoid it?”

“You can’t,” Agata replied. This was the sticking point they always reached. “Not if the disruption is the proof that it hits us.”

“Then what difference does it make ‘who we are’ and ‘what we do’?” Azelio asked bitterly. “If I go through the motions of enacting something more benign … how will that help? If there’s a murderer trying to kill your family, you don’t protect them by moving your own tympanum to match the threats being shouted through the door. Or do you really believe in safety through reverse ventriloquism?”

Agata wrapped her arms around her head in frustration. “We don’t know that there’s a murderer at the door! We don’t know that there’s a meteor on its way!”

“So we search the sky,” Azelio pleaded. “We make better detectors. We try to peek through a crack in the door.”

“If we were going to find anything,” she said, “we’d know that already. If we were going to spot a meteor and avoid it, then that’s what the messages would be telling us.”

Azelio said, “I can’t accept that.”

Agata dropped her arms. “I know.” There was nothing she could say that would change his mind, and nothing she could do that would bring him any comfort.

“We should fly over the antipode,” Tarquinia joked. “Do a little reconnaissance.”

“Fly low enough and you could occult all the channels at once,” Ramiro suggested. “Maybe there’s a disruption earlier than everyone claimed, and all the later messages are just fakes.”

Agata said, “I’d rather not test the defenses.”

Through the window, the mountain cast a sharp silhouette against the star trails. It had been visible through external cameras for days, but they’d had to wait until they cut the main engines to rotate the Surveyor around for a naked eye view.

“Ah, look at that!” Tarquinia gestured at her console, which was displaying a feed from the telescope. “I think we’ve found a Councilor at home.” The gray hull that the instrument had picked up was lurking in the void, far from the Peerless. It wasn’t quite identical to the Surveyor, but the overall design was eerily similar. Agata wasn’t shocked that anyone with the means to do so had withdrawn to a safe distance from the mountain, but it was dismaying to see that Ramiro’s guess had been right: even Verano had lost his powers of originality.

Azelio joined them, taking his seat and murmuring greetings. As subdued as he was, he seemed ready to make an effort to get through the formalities to come. Agata wished she could have assuaged his fears, but from a coldly pragmatic position she couldn’t help thinking that his forlorn demeanor might serve as useful camouflage. No one observing the whole crew together could imagine them possessing even the shyest hope of influencing the fate of the Peerless.

Tarquinia brought the Surveyor spiraling in toward the docking point, and as the mountain finally hid the stars Agata felt a rush of pure joy. She wanted to burrow deep into these old, familiar rocks again, to drift along the core of an ancient stairwell, to gaze across a field of wheat that stretched beyond the ceiling’s horizon. She glanced over at Azelio and he met her gaze with a look of shared relief, the sheer force of belonging overpowering his anxiety. How could they not feel safe here?

Tarquinia opened the link to the Peerless, and Verano appeared on her console. “We’ve brought your creation back in one piece,” she said. “But I suppose you always knew we would.”

“From the start,” Verano replied. “No messages required.”

Agata knew she was off-camera herself, but when Ramiro’s slight movements caught her attention she didn’t dare turn to look at him directly. If she didn’t see him start up the software that set the flock of occulters loose—before erasing itself from the communications system—the act wouldn’t linger in her mind as they faced the scrutiny of the welcoming party. There was no predicting the full array of sensors and cameras aimed at them as they approached, but Tarquinia had lit up a docking beacon at the front of the Surveyor. As the occulters moved away from the literal blind spot directly behind the hull, the glare should be enough to allow the tiny devices to reach the slopes undetected.

Agata watched with a glorious ache in her chest as Tarquinia maneuvered the Surveyor into the cradle of ropes that hung below the airlock. When the air jets cut out they were weightless for a flicker, then the net was holding them, swaying slightly.

She turned to Azelio. “Can I tie my belt to yours when we go up?” she joked. “You’re the only one of us who’s heard clear testimony of their safe arrival.”

Azelio buzzed. “You’re not counting Greta and Ramiro?” Ramiro said, “I’m not counting Greta and Ramiro. I could fall into the void right now, and she would still have gloated about how miserable I was going to look at the reunion.”

They donned their helmets and attached the air tanks to their cooling bags. The interior would remain pressurized as they disembarked for the sake of Azelio’s plants.

“Agata’s first,” Tarquinia decided.

Agata looked around the tilted cabin, wondering how much ill-behaved dust they’d brought back from the time-reversed world. She was wearing a pouch full of papers under her bag, and all her formal notes had been transmitted to Lila long ago, but she hesitated, afraid that she might have left something important in her cabin that the decommissioning team would discard as waste. But she’d returned all of Azelio’s drawings to him, and her photograph of Medoro was with her, next to her skin.

She clambered up the guide rope and entered the airlock. When she closed the door behind her and started pumping down the pressure, she felt her hands shaking; for all her nostalgia, she wasn’t sure that she was ready to face a whole crowd of non-crewmates in the flesh.

She steadied herself and opened the outer door. The rope ladder was dangling against the hull; when she gazed straight up she could see the lights of Verano’s workshop through the portal above. She resisted an urge to peer out across the slopes; if she really had a chance of discerning one of the occulters clinging to the rock from this distance, the whole scheme really was doomed.

Agata climbed through the portal and ascended into the clearstone chamber from which she’d departed twelve years before. She could see a small crowd gathered in the workshop; they seemed to be chatting among themselves, though no sound reached her in the evacuated chamber. A few people turned to stare toward her with expressions of mild interest. She spotted Gineto, Vala and Serena with a young girl who had to be Arianna. None of them waved to her, and for a moment Agata wondered if she’d aged beyond recognition, but then she realized that between her helmet and her cooling bag she was effectively disguised—assuming that no one would bother to mention in their messages that she’d been the first to arrive.

Azelio came up the ladder then stood for a while surveying the scene. “I don’t see any Councilors here to greet us,” he said. “Five stints until the disruption, and they’re still too afraid to visit the mountain.”

“Are you sure there are none? We might not recognize the new ones.” There’d been an election not long after the Surveyor had departed.

“There are no new ones,” Azelio replied. “Girardo told me that the incumbents all kept their seats.”

Ramiro climbed through the portal. “I suppose it’s too late for me to make a run for freedom now.”

“They’re not going to put you back in prison,” Agata scoffed.

Ramiro was amused. “You mean, seeing as the whole sabotage thing is no longer an issue?”

“Someone would have mentioned it,” Agata suggested. “Greta might have lied, but someone would have told you the truth.”

“I didn’t call anyone who would have told me the truth,” Ramiro replied. “If I’d wanted to know my future, I would have been on your side from the start.”

Tarquinia joined them, closing the portal behind her and sealing the rim. She spent a moment assessing the gathered crowd. “And I thought we were the ones who’d look half dead. Let’s get this over with.”

Ramiro pulled the lever to repressurize the chamber. Agata felt her cooling bag sagging against her skin. Azelio was closest to the door; he struggled with the crank, leaning down with all his weight to apply enough force to break the seal. Agata followed him out but then hung back, struggling to adjust to the vastness of the room, the hubbub of voices, the strange, sharp smell of the air.

Azelio took off his helmet and placed it on the ground then strode toward his family. Agata watched the odd expression on the children’s faces: as happy as they were to be reunited with their uncle, they looked bored and fidgety as well. It was as if he’d been playing this game with them for the last three years, the returning adventurer coming through the same door again and again. They’d seen the video message that Azelio would soon make with them, and however fresh it might have appeared at the first viewing, by now their parts in it would be mere recitations.

Agata removed her own helmet and started walking toward Medoro’s family.

“Agata!” Serena finally recognized her and ran forward to embrace her. “How are you?”

“Old. Don’t squeeze me too hard.”

“If that’s loose skin, you’ll need medical attention urgently,” Serena joked, bumping up against Agata’s papers. Vala joined them, followed by Gineto carrying Arianna. As they exchanged hugs and greetings with her, chirping with pleasure, Agata wondered if the adults were simply humoring her. But Azelio had been so intent on reassuring Luisa and Lorenzo throughout his long absence that he’d robbed them of any real joy at his arrival. So long as none of her own friends sent back every detail of this encounter, it need not be devoid of all spontaneity.

Serena said, “You’ll have to forgive me if I seem jealous.”

Agata was bewildered. “Of what?”

“You did more or less meet the ancestors,” Vala interjected—gently teasing her daughter with the hyperbole.

“So everyone’s seen the pictures of the inscription?” Agata had never been sure how people would respond; a part of her had been afraid that the find would be written off as a crude fake by an ancestor-worshipper. “They’re taking it seriously?”

“Of course!” Serena replied. “That was the biggest news at the start-up, apart from the … other thing.” She glanced over at Arianna, making it clear that they weren’t discussing the disruption in front of her.

Gineto said, “It’s the only reason I voted to keep the system running after the trial: we needed a piece of good news like that.”

“You changed your vote?” Agata was surprised, and a little disturbed. This sounded like a rationalization for putting himself on the winning side.

“It would have been hypocritical to claim that I wished I hadn’t heard about the inscription,” Gineto insisted.

“But if the majority vote had been to shut down the system—?”

“As I said, the inscription was my only reason,” Gineto replied.

“What was the vote?” she asked him. “Do you remember?”

“Less than one in a gross against.”

Agata fell silent. If the system had stretched on unbroken all the way to the reunion, as she’d once imagined—endorsed at referenda again and again—would its persistence have been a true measure of its virtues, or just a self-affirming stasis, as pathological as the innovation block?

She glanced across the room and saw Ramiro talking to his sister; he did look shockingly old beside her, and her children impatient to be somewhere else.

An archivist with a camera separated herself from the crowd and called to everyone to move into position. “What position?” Agata asked. Then she understood.

Serena said, “Don’t worry, it’s not as if you can get it wrong.” But as the group squeezed together to fit into the shot, she seemed to be looking around for reference points herself, anxious to conform to her own recollection. What happened, Agata wondered, to the woman or man whose nature demanded of them that they find a different spot or adopt a different posture than the one recorded in the famous image of the Surveyor’s return? That urge would have to have been beaten out of them somehow, or they would have been absent from the picture all along.

Agata turned to face the camera. In her rear gaze she could see people trying out their expressions, as if their imitations could fail to be perfect. As the archivist raised her camera, Agata struggled to hide the shame she could feel beginning to show on her own face. Perhaps it was the proper response to the plight she’d helped to foist on the mountain, but she didn’t want the whole of the Peerless seeing her reach that conclusion, three years before she’d reached it herself.

“I’m here to see my brother, Pio,” Agata told the guard.

The woman held out a photonic patch, connected to the wall by a cable. “Form your signature.” Agata brought the squiggle onto her palm and pressed it against the patch.

“Valuables?”

Agata handed over the key to her apartment.

“Do you still have any pockets?”

“No.”

“Please resorb all your limbs.”

Agata hesitated, wondering what would happen if she argued, but then she released the guide rope and complied. Her torso drifted slowly toward the floor of the entrance chamber; the guard intervened and caught hold of her with four hands, then she began prodding Agata’s skin with her fingertips, searching for any concealed folds. Agata closed her rear eyes and turned her front gaze toward the ceiling, wondering if the guards had access in advance to the outcomes of these searches. Why should they look too hard, if they knew they’d find nothing? But if there was well-hidden contraband, a tip-off might enable them to find it more easily. Or would that be yet another unlikely loop, self-consistent but hugely improbable?

When it was over, the guard let Agata fall, leaving her to reshape herself and catch the rope again. “This is your pass,” the woman explained, handing her a red disk. “Please don’t lose it.”

“Do I lose it?” Agata asked.

“Of course you don’t,” the guard replied. “Because I asked you not to.”

“Right.” Agata suppressed a shiver.

“Visiting room three. Go through.”

Agata pushed open the swinging doors and followed the corridor into the prison complex. It was quieter than she’d expected, given the number of people still interned; all she could make out were some faint scraping noises in the distance, barely audible over the twang of the guide rope as she advanced. The two visiting rooms she passed were empty; she entered the third and harnessed herself to the desk. As she waited she forced herself to glance around the room—she didn’t want to be seen searching obsessively for the cameras, but to have stared at a fixed spot on the wall and shown no curiosity about her surroundings would have been equally suspicious.

She struggled to keep the possibilities straight in her mind: if the authorities were going to catch her conspiring with saboteurs then they would have known that for the last three years—but they couldn’t arrest her until she’d had a chance to do whatever deed revealed her guilt. Once she’d been arrested, though, even if they kept that from becoming public knowledge, surely Lila or Serena would notice her absence and send her a message about it? Or better yet, send a message to their earlier selves to be passed on to her in person; that would be less likely to be detected and intercepted.

So was the lack of any warning a proof that she wouldn’t be caught? Or did the fact that she’d received no messages at all from her future self mean that everything would turn bad very quickly?

Agata heard a door creak open in the distance, then the clank of hardstone links, an almost rhythmic sound as the prisoner approached. When the guard escorting Pio reached the doorway, Agata loosened the harness and pulled herself closer, but she still couldn’t see her brother.

“Please stay back,” the guard instructed her. The woman held a loop of chain in one hand. She dragged herself over to the wall and attached it to a clamp, then turned and said, “Come.”

Pio pulled himself into the room along the guide rope, moving nimbly despite the stone bar that transected his torso. “Hello Agata,” he said.

“Hello.” For a moment she was numb, then the sight of his gaunt frame was too much and she started humming softly. She was far from convinced of his innocence, but no one had come close to establishing his guilt. If he had murdered Medoro and the others then he deserved to be locked up until he died—but what did she know for sure? Only that he’d viewed the messaging system with the same degree of alarm and revulsion from the start as she now felt for it herself.

The guard watched as Pio climbed into the harness on his side of the desk. “You have three chimes,” she told Agata, then she withdrew into the corridor.

Agata composed herself, but she reached over and squeezed her brother’s shoulder while the gesture still had a chance of seeming innocent and spontaneous. In the flicker before her palm touched his skin, she formed the words: On your side. Tell me how to help. She tried not to worry about how long it would take him to read the message if he hadn’t been expecting it; the action had a natural time scale of its own, and if she over-thought it that would show.

Pio leaned back and examined her appraisingly. “Detours really do work the way they taught us in school,” he marveled. “Twelve years in that box. How did you stay sane?”

“The time passed quickly,” she said. “After the first year.”

“I can’t say the same, though maybe with the ratios it almost evens out.” He buzzed suddenly. “Cira told me about your big discovery. The ancestors don’t burn, we don’t wipe ourselves out—what could be better than that?”

“People acting on it,” Agata replied. “I thought I’d come back to find that everyone had buried their differences.”

“Not yet.”

Agata didn’t want to start interrogating him about his views on the disruption, but it would seem strange if they didn’t discuss it at all. “Do you think the Councilors are going to pull the plug?”

“Why would they do that?”

“They’ve seen the problems the system’s created,” she said. “We can’t spend the next six generations stuck with the same technology.”

“But how would they explain the shutdown afterward, without admitting that they’d planned it all along?” Pio wondered.

“They could claim that there’d been some kind of minor impact,” Agata suggested. “With just the right size and trajectory to take out all twelve channels at once, but do no real damage elsewhere.”

“All of which they’d more or less guessed, of course. But lacking proof, they couldn’t announce it officially.” Pio inclined his head. “It’s possible, I suppose. We’ll know soon enough.”

“Yes.”

Pio changed the subject. “Are you going to see Cira?”

“I don’t think so.” Agata supposed it might sound suspicious that she was prepared to reconcile with Pio but not her mother, but she wasn’t a good enough actor to pull off that encounter, and Cira would have much less motivation to play along. “If she’s stood by you, that’s admirable, but I think she and I reached the point a long time ago where we’ll be happier if we stay out of each other’s way.”

“I understand.”

“Can I bring you anything?” she asked. “They let you have books, don’t they?”

“I can always use more paper and dye,” Pio said. “I’m writing a book of my own.”

“What kind of book?” Agata couldn’t help mocking him a little. “Surely there’s no need for a migrationist manifesto now?”

“It’s a history of women and men,” he replied.

“You mean the discovery of shedding—that kind of thing?”

“More or less. You can read it when it’s finished, if you like.”

Agata couldn’t imagine what he thought he could add to the version in the archives, but if he had a project to help him pass the time that could only be a good thing.

When the guard returned to fetch him, Pio leaned across the desk and executed an awkward hug. As he drew back, Agata was still trying to memorize the sensation of his palm on her shoulder.

“Will I see you again?” he asked.

“Of course,” she replied. The guard looked amused; apparently not in the next five stints.

Agata sat at the desk for a while, self-consciously pensive, her palms resting on her thighs as she passed copies of Pio’s tightly scrawled instructions back and forth between the two hidden patches of skin.

The food hall was close to the rim of the Peerless, and even at the second bell it was crowded. Agata entered and queued at the counter, trying to remain unfazed as she noticed people looking her way twice, probably recognizing her from the archival image of the Surveyor’s return. At least their faces showed a flicker of surprise, proving that they wouldn’t make so much of the encounter that they let themselves know about it in advance.

She’d barely slept the night before, and then as she’d prepared to leave her apartment her console had beeped and offered up a message from her future self:

I still don’t agree.

It would be sent three stints before the disruption; that didn’t quite prove that she’d be walking free right to the end, but it was more reassuring than absolute silence. And if the meaning was opaque to her at present, she could only hope that anyone spying on her would find the lack of context unremarkable. There was no reason for anyone’s private messages to spell out every detail of the dilemmas they were intended to resolve. The bandwidth quotas weren’t infinite: gnomic brevity would generally be a virtue, not a sign that the sender had something to hide.

When her turn came at the counter she asked for two plain loaves; she’d discovered after the welcoming party that her gut no longer appreciated fresh spices. She carried the food to the corner farthest from the entrance, where an awkwardly placed cooling vent discouraged most diners. The present crowd left few enough alternatives for her choice not to seem too perverse.

She sat on the floor and ate slowly, her front eyes on her food, her rear gaze to the wall.

She was halfway through the second loaf when a man addressed her.

“Did you drop these?” Agata looked up. There were three coins on his outstretched palm; she squinted at them, memorized their value, then said, “No, they’re not mine.” “Sorry to have troubled you.”

Pio hadn’t told her how long she should wait, so as soon as she’d finished eating she left the hall and headed for the address indexed by the coins’ denominations. The area wasn’t familiar to her, but as she ascended the stairs toward the axis then dragged herself along the corridor toward her destination, the smooth texture of the rock beneath her feet and the red tunnel of the moss-lit walls were enough to induce an ache of recognition. The death of every traveler save a handful of evacuees was beyond her power to imagine, but she’d come as close as anyone alive to feeling the absence of the mountain itself. If she needed a vision of the loss she was fighting to prevent, she could think of the Peerless retreating into the distance, shrinking to a dark speck against the stars and then vanishing.

Outside the door she hesitated, but she’d have to trust Pio’s comrades to have chosen an appropriate level of precautions, and the innovation block to have kept the Council from automatically tracking everyone, everywhere. She knocked firmly, and after a few pauses the door swung open and a man invited her into the apartment.

“My name’s Giacomo,” he said.

“I’m Agata.” She closed the door behind her. “Can we talk freely?” “Absolutely,” Giacomo assured her.

There was no point in prevaricating. “I want to help shut down the messaging system,” she said. “We have a dozen and six small machines out on the slopes, capable of moving along the rock and flying for short distances. If you can tell us exactly where to send them, we can use them to occult the orthogonal stars for all of the channels.”

Giacomo hesitated before replying, but only as much as politeness required. He must have had years to consider her offer.

“The system uses light from the entire orthogonal cluster,” he said. “It’s not a matter of one star per channel. To shut it down, you’d need to blot out half the sky from twelve different vantage points.”

“The entire cluster?” Agata had always pictured a single star as the light source. When Medoro had first raised the idea with her, he’d started with a thought experiment where a distant object passed in front of a time-reversed star—and if the object had to be remote enough for the time the light spent in transit to be significant, it could hardly block out anything larger. But once you folded up the light path with mirrors, the same constraints no longer applied.

“The optics gathers light from all directions visible from the base of the mountain,” Giacomo explained. “Or sends it out, if you want to talk in terms of our arrow, but it’s easier for me to imagine the whole thing working backward. All that each channel needs is a reliable light source that it can block or reveal with a shutter. Combining all the light from across the cluster makes the source brighter and more dependable.”

“And less vulnerable to sabotage,” Agata conceded. She’d convinced herself that the Councilors would be relying on secrecy, each one guarding the coordinates of their chosen star. Instead, they’d adopted a robust solution that could not be undermined merely by the revelation of a couple of numbers.

“But your machines will still be very useful,” Giacomo said encouragingly. “I can promise you that.”

“How?”

“They’ve been part of our plan for years. They won’t be able to block the channels with their presence alone, but they can still carry explosives to the sites where they’re needed.”