“Humans live in all of these star systems, but the planets in most of these star systems aren’t the kinds that are good for human life.” Marce zoomed into Hub again. “Hub, for example, is airless and tidally locked. That means one side of the planet is always facing the sun, so it’s super-hot, and the other side is facing away, which makes it frozen. Humans on Hub have to live under the ground to survive.”

  He zoomed out and picked another system. “Here in the Morobe system, the only planets are gas giants—huge planets that don’t even have a surface to land on. We couldn’t live on those. These planets have moons but most of them aren’t very suitable for humans either. So here we live in space habitats, positioned in spots called Lagrange points, or in other places that can be made stable. So that’s how most humans live now: underground on rocky planets or on large space habitats. There’s only one place in the Interdependency where humans live on the surface of the planet.”

  Marce zoomed out and in again, back to End, which hovered on the screen, a blue-green marble, clouded in white. “That’s us. That’s End.”

  “What about Earth?” one of the children asked, as one of them always did.

  “Good question!” Marce said. “Earth is where humans originally come from, and like on End, you could walk around on its surface. But the Earth isn’t part of the Interdependency. We lost contact with the Earth over a thousand years ago when the single Flow stream to it disappeared.”

  “How did that happen?” It was the adult again, who was immediately shushed by one of the other adults. Marce smiled at this.

  “It’s complicated,” he said. “The best nontechnical answer I can give you is that everything in the universe is constantly moving, including star systems, and that movement sometimes affects the Flow. Basically, the Earth moved, we moved, and the Flow stream went away.”

  “Can it happen again?”

  “Bint!” someone said, to the adult asking questions, admonishing him.

  “Look, I want to know,” Bint said.

  “It’s all right,” Marce said, holding up a hand. “In fact, it did happen again, more than seven hundred years ago, when we lost contact with a system called Dalasýsla. This was before the local Flow streams were as extensively mapped as they are now. The Flow stream to Dalasýsla was apparently already collapsing when it was first colonized, it just took a couple hundred years to close entirely. Now, as it happens, the rest of the Flow streams in the Interdependency have been robust and mostly unchanged for the last several hundred years.”

  This seemed to satisfy Bint, and Marce was happy this fellow hadn’t noticed he didn’t actually answer the question.

  From a distance, a low crummp made it into the momentary silence of the planetarium. One of the adults in the audience started to take in a sharp breath, and then stopped.

  “And I think that’s about all the time we have for today,” Marce said. “Thank you all for coming, and I hope you’ll come again another time. We’d love to see you.” A day when someone isn’t clearly shelling someone else only a few klicks away. He flicked up the house lights and waved good-bye to the children as the adults filed them out of the room. One of the adults looked back and mouthed the words thank you to him. Marce smiled and waved again.

  “Still giving tours in the middle of a war,” said someone new, in the back of the planetarium. “That’s noble. Stupid, but noble.”

  Marce looked up, saw who it was, and smiled again. “Well, technically, we are nobility, aren’t we, sis?”

  Vrenna Claremont, in her full constable uniform, smiled back and started walking down toward her brother. “Being a noble on End is like being the richest person in a trash heap. It doesn’t mean much. Especially now, when the duke is about to get his ass handed to him and rebels are running about liberating his property. It’s not a stretch to assume other nobles will find their stuff similarly liberated.”

  “My stuff is a bunch of books in graduate housing,” Marce said. “I think they’ll be disappointed.”

  “You’re a professor now. You should move out of graduate housing.”

  “I’m resident master. Saves on rent.”

  “A count’s son, worried about rent,” Vrenna said.

  “We are really unimpressive nobility, it’s true.”

  There was another crummp somewhere in the distance, and it didn’t sound as distant as the last one.

  “I’m doing a really good job of not panicking right now,” Marce said.

  “I noticed that,” said Vrenna. “I mean, I wasn’t going to mention it. But I noticed it.”

  “We can’t all have ice water in our veins.”

  “I don’t have ice water in my veins. I just know how far away those explosions are, so I’m not going to worry about them right now.”

  “How far away are they?”

  “About five klicks. The docks, where the duke’s forces are trying to bury a contingent of the rebels under shattered cargo containers. It probably won’t work. Most of the rebels are long gone from there, moving to occupy strategic resources. You and I are going in the other direction anyway.”

  “We are?”

  “Yes. Dad sent me to collect you.”

  “Why?”

  “One, because there’s a war on, and although I don’t expect that shelling is going to get any closer, there’s no guarantee the university, including your graduate housing, isn’t going to be on fire by the time the sun sets today.”

  “That bad,” Marce said.

  Vrenna nodded. “Yup. You may not remember this, but the house has a watch set on it by the Imperial Marines. If a rebel comes within a klick of it they’re likely to be vaporized from space. That makes it the safest place on the surface of the planet right now.”

  “Did Dad tell that to the duke?”

  “You know, I think he might have skipped mentioning that to him.”

  Marce grinned again at that.

  “Two, Dad wants to show you something.”

  “What is it?”

  “Data.”

  “Anytime you want to be less ambiguous, Vren, that’d be great.”

  “He said you would know what it was, and that it wouldn’t be something we’d talk about out loud in public.”

  “Oh,” Marce said.

  “Yup.”

  Another crummp.

  “That sounded closer,” Marce said.

  “It wasn’t. But we should leave anyway. We wait any longer, someone might take it into their heads to start taking potshots at the skimmer.”

  * * *

  Someone took a potshot at the skimmer anyway, several times during the flight.

  “Go faster,” Marce urged his sister.

  “Anytime you want to fly a skimmer just over the city rooftops, without crashing into some random chimney, you let me know,” she replied.

  In lieu of bothering his sister further, Marce looked out the skimmer bubble at the streets of Opole. Most of the residential streets were untouched, with only a few glimpses of people carrying things out to their cars, as if packing for a move. The main streets, however, were clogged with cars, and several were jammed to a standstill.

  That took effort; Marce suspected some drivers had disabled autodrive to take control of their cars directly, either in a panic or because they suspected the government was somehow going to disable their movement. The end result either way was that these newly independent cars were messing things up for everyone else.

  And every now and again, Marce would see columns of soldiers moving along the streets, armored vehicles among them, off to secure and/or liberate one strategic element of the city or another.

  “This isn’t going to end well,” Marce said to his sister.

  “Does it ever?” she asked, banking toward the Warta, the wide river that ran through Opole. She flew the skimmer to the middle of it, far enough away from either bank to discourage any further potshots. Marce suspected that technically his sister was flying the skimmer illegally—skimmers were
supposed to use automation and stick to specific air routes within the city to avoid problems with other air traffic. The middle of the Warta was not one of those routes. He also suspected that today local law enforcement had other things to worry about.

  Presently the skimmer left Opole behind and the land rose into rolling hills, the Warta meandering gently between them, suburbs and then rural villages nestled up against their inclines. A small tributary of the Warta branched off, into another set of hills; Vrenna followed it and within minutes was at the house.

  “The house” was technically Claremont Palace, named for the province district that their father had been made count of, nearly forty standard years earlier, and from which the family now took its name. There had been a previous count, whom Marce had never met, having not been born yet; he had been persuaded to give up the title by accepting an appointment to the imperial court. The story Marce had been told was that the fellow needed very little convincing. Better to be a functionary at court than a noble on a planet of exile. The previous count departed so quickly he left most of his furniture and at least a couple of pets, cats who had been perfectly fine with the new tenants, his father had told him, so long as the food kept coming.

  “Come on,” Vrenna said, as they stepped out of the skimmer, on the landing pad near the garage. “Let’s not keep Dad waiting.”

  Their father, Jamies, Count Claremont, was in his office, watching the revolution on the wall monitor. He saw them enter and pointed to the monitor. “Look at this nonsense,” he said to them.

  “Welcome to the revolution,” Vrenna said.

  Jamies snorted. “It’s not a revolution. The ‘rebels’ are probably funded by merchant guilds who want an import tax break. Or something. The duke wouldn’t allow it. Or something. So the ‘rebels’ will take down the duke and install an ambitious noble in his place, who will cut the tariff. It’ll be rubberstamped by the emperox, because no one out there cares what happens to End. And because they think in another twenty years we’ll all just do it again.”

  “Won’t we?”

  “Not this time.” Jamies went to his desk, retrieved a tablet, and handed it to Marce. “We finally got it. The smoking gun. And the last bit of data I needed for the prediction model.”

  Marce took the tablet and started scanning through the work there. “When did this happen?”

  “Six weeks ago. A ship called Tell Me Another One experienced a Flow anomaly and then recorded a transient Flow shoal, consistent with my model. It’s observed, recorded, verified, and tracked. Everything about it fits. Everything about it is exactly what we’ve been looking for. It confirms everything we’ve suspected about the Flow.”

  Marce stopped trying to scan the work, which would require hours for him to read and ingest, and looked to his father. “You’re sure about this.”

  “Do you think I would tell you if I wasn’t?” Jamies said. “Have you ever known me to be anything other than exceptionally careful about this hypothesis? Do you think I didn’t throw everything I could at it to disprove it? Do you think I want it to be accurate?”

  Marce shook his head. “No, Dad.”

  “Don’t get me wrong, Marce. I need you to read it. I need you to tell me if there’s anything I’m missing. Anything I’ve overlooked. Because as much as the scientist in me is thrilled to have made this leap in understanding the physics of the Flow…”

  “… as a human being you want to be wrong,” Marce finished.

  “Yes,” Jamies said. “Yes, I very much do.”

  For as long as Marce could remember, Dad had called it “the Family Secret”: his father’s examination of navigation data from every ship that had ever come to End over the last four decades. Officially Count Claremont’s role for the empire was chief imperial auditor for End. He examined the data to assure that none of the ships ever deviated from the imperially approved trade route—and thereby avoided the trade tariffs and other taxes that were required of them—that were often planned years or even decades in advance. In this, the count was one of dozens of chief imperial auditors, one in every system, who made sure money stayed where it was supposed to stay: in the pocket of the emperox first, guilds second, and everyone else somewhere rather further down the line.

  In reality, Jamies, Count Claremont, didn’t give a shit about any of that nonsense. He performed the role of chief imperial auditor well enough, primarily by delegating it to underlings with the admonition that any graft too obvious to be ignored would have to be punished. But that wasn’t why he came to End, or why his friend, the Emperox Attavio VI, had sent him. He had been sent to examine the navigational data of the ships for discrepancies, but not of trade. He was looking for data that backed up his hypothesis, first formulated while he was still an undergraduate at the University of Hubfall, that the Flow streams that defined the Interdependency did not benefit from “robustness through resonance”—the theory that the unusual density and interaction of Flow streams within the Interdependency helped to create a stable waveform within the Flow that would keep those streams open and unchanging for millennia.

  Jamies read the math behind the theory and surmised what others didn’t, or did and preferred not to believe: that “robustness through resonance” was data-fudging nonsense, and that the collapse of the Flow streams to Earth and Dalasýsla were precursors, rather than the exceptions that modern Flow theory held them out to be. He said as much to his friend Batrin, the newly crowned Emperox Attavio VI, showed him the data, and warned him that a collapse could happen within the century.

  Batrin saw the possibility of validity in the data. He also recognized that it represented a threat to the trade and stability of the Interdependency, and would likely be considered blasphemy by the church. So he did two things for his friend Jamies. First, he bribed him into silence by making him a count. Then he sent him to End, as far as he could be sent in the whole of the Interdependency, and gave him a job that would give him the data he needed to verify or dismiss his hypothesis, and told him to tell no one but him about the work.

  Which Jamies did, mostly. First he told his wife, Guice, and then after their twin children Marce and Vrenna were old enough, told them too. He assumed the emperox wouldn’t mind. Guice took the secret to her tragic, early grave. Vrenna kept the secret because she was good at secrets. Marce kept it because once he showed enough interest and aptitude in the physics of the Flow, Jamies relied on him to check his work.

  Now, all the years of quiet, methodical data collection and interpretation had paid off. Jamies, Count Claremont, had verified the most important discovery in human experience since the discovery of the Flow itself. If it were known to other scientists, they’d shovel every single possible award they offered onto him.

  That is, if the Interdependency were still around for them to do so.

  “So it’s true, then,” Vrenna said, to her father and brother. “The Flow is collapsing.”

  “The Flow is the Flow,” Jamies said. “It doesn’t do anything. Our access to it, on the other hand, is definitely going away. The unusual stability of the Flow streams that have allowed the development of the Interdependency is coming to an end. One by one, the streams are going to dry up. One by one, the systems of the Interdependency are going to find themselves alone. For a long time. Possibly forever.”

  “How long do we have?” Vrenna asked.

  “Ten years,” Marce said. “At the outside.” He glanced over to his father. “If Dad’s models are perfectly accurate, less than that. Probably closer to seven or eight years before all the local Flow streams are gone. Most of them will be gone before then.”

  Jamies turned toward his son. “And that’s why you must go.”

  “Wait, what?” Marce said.

  “You have to go,” Jamies repeated.

  “Where?”

  “To Hub, of course. You have to take this data to the emperox.”

  “I thought you were sending regular updates to the emperox,” Vrenna said, to her father.
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  “I have been, obviously. The data is encrypted and sent monthly via outgoing ships.”

  “So send this the same way,” Marce said.

  Jamies shook his head. “You don’t understand. It’s one thing to keep the emperox updated when I’m just crunching through the data and refining the model. It’s another thing entirely when the model is verified, and real, and a threat to the Interdependency. He’s going to need someone to walk him through it all. And then walk everyone else through it. And then argue with everyone from scientists to politicians who want to poke holes in it for their own purposes. Someone needs to go.”

  “I agree,” Marce said. “And that person should be you.”

  Jamies opened his mouth but then Doung Xavos, the count’s secretary, poked his head into the room. “My lord, Lord Ghreni Nohamapetan is here to see you. He says he comes at the request of the duke.”

  “Bring him,” Jamies said, and looked at his children.

  “Should we go?” Vrenna asked.

  “I’d rather you stayed.” Jamies gestured at the monitor spilling out the news of the revolution; it switched itself off. Jamies sat at his desk and encouraged his children to sit as well. They did.

  Lord Ghreni Nohamapetan entered the room, clad in black, and Marce watched as the noble went to greet his father. Ghreni and the Claremont siblings were of an age, but the two of them had never socialized extensively with the Nohamapetan scion; he’d arrived to End only a few years prior to handle his house’s interests. They’d seen him once or twice at functions at the duke’s palace and had once been formally introduced to him. Marce recalled Ghreni scanning the both of them quickly, to see if there was any political advantage in knowing either, and when the apparent answer was “no,” politely ignoring them from there on out. Marce was still mildly annoyed by this; Vrenna found it amusing, because of course she would.

  “Count Claremont,” Ghreni Nohamapetan said, bowing.

  “Lord Ghreni,” Jamies said. “A pleasure.” He gestured toward Marce and Vrenna, who stood. “You remember my children, no doubt.”