Saia observed Serit's every movement from her room, her domain expanded to include most of the building. She'd stayed inside the previous evening, then she’d been deactivated as usual for the night. She only found out in the morning that the warehouse had filled with guards during the night. There were two for every entrance on the bottom floor, two in the kitchen, two for each segment of the corridor, and two inside the laboratory, where Serit's research was still sprawled on top of the table.

They had tried to enter, but the guards forbade it and made them return the key. So they'd spent most of the time in their room, jotting down their research on paper and story-bottles from memory. Saia could read both their original notes and the new version and notice the differences. She didn't understand the content, but the original included a lot more details. Serit seemed to know that too, since they stood every few minutes to pace around the room, mumble with themselves, and sometimes cry.

Halfway through the morning, someone knocked at the main entrance of the warehouse. Saia didn't need to expand her domain further to see who it was, since the storage room of the warehouse was just under her own, and the floor that divided them was thin.

Hilon showed her documents to the guards inside.

“I’m here to take the sphere with me,” she explained. The guard pointed at the stairs.

Saia stood from the bed and grabbed her bag. She didn't know what else she could bring with her in addition to what it already contained. She reexamined the tunics and story-bottles in her cabinet while Hilon's steps approached from the end of the corridor. She stopped before reaching Saia's room, knocking at Serit's instead. Saia leaned with her back against the door, domain expanded the minimum amount she needed to watch them and listen to their words.

“… approved the project?” Serit was asking.

“Yes.” Hilon walked straight up to the window and opened it. “Which is good, since we already have a prototype. I'd hate having to dismantle everything.”

She sat down on the only chair while Serit plopped onto the bed.

“How is it going?” she asked.

They shrugged.

“I received a letter this morning. The representatives are deciding what to do with my research, whether to destroy it or keep it somewhere else. The only certainty is that they'll take it away from me.”

“Enanit wants to destroy it?”

Serit shook their head.

“Izha. The others want to preserve it, but he was too scared by what he has seen. He thinks the existence of this research is a risk in itself, especially now that there are those rebels around.”

Hilon nodded distractedly, looking out of the window.

“Have you thought about working from here?”

“I want to, but…”

“You don't have your tools at disposal.”

“Exactly.”

They stayed in silence for a bit.

“I was thinking about this last night,” Hilon said. “And I have an idea on how to free both you and your research.”

Serit glanced at the door, as if expecting a guard to burst through at any moment.

“You mean... You have arguments to convince the representatives that it's a good idea?”

Hilon smiled and leaned forward, elbow propped against the desk.

“I mean faking another kidnapping.”

Serit was sitting with hands over knees, eyes wide as they gripped the cloth of the tunic.

“You mean like the rebels did?”

“Exactly. After what you said yesterday, the representatives won’t be too surprised if they make a third attempt while you’re confined here.”

“And then?”

“And then I have a small house on the third level with all the equipment you might dream of. You'd have a lot more freedom than you'd have here, if you're careful.”

“Let's say I agree, who would actually be kidnapping me?”

“You have friends on the fourth level, right?”

“Yes, but I'd rather not involve them in something this dangerous.”

Hilon relaxed with her back against the chair.

“Then I'll find someone among my workers. It shouldn't be difficult if I promise the right things. Knowing the placement of the guards and having you on the inside, it shouldn't be too difficult.”

Serit was growing more nervous by the second, now hugging their knees to their chest.

“What if they get captured, or the representatives find out you're hiding me somewhere?”

“We'll act at night and create a distraction. I'll make my workers aware of the risks and recompensate them accordingly. I won't deal with them personally, so they won't know who sent them even if they accept to have their memories examined. And if they'll find you in my house, I can always say I saved you and was protecting you after the attack.”

“I don't like this, Hilon. I'd rather not do anything and just wait.”

“And lose your research?”

That gave Serit pause. They looked at the floor with the expression of someone who was about to cry with frustration.

Several seconds passed before Hilon spoke again.

“There's no time, Serit. If you want my help, we'll have to act tomorrow night.”

They hesitantly nodded, then sighed.

“I’ll write the schedule of the guards with our code.”

Hilon put a hand in a pocket of her tunic.

“Actually, use this one.”

Saia had to focus her view on the piece of paper she handed Serit to see what was written on it. It was a card with circles and letters similar to the ones she'd used with her herlamis team.

Serit took it carefully by a corner, in order not to stain the viss on the card with their own. Hilon stood and gave them a pat on the shoulder, a tired smile on her lips.

“Be brave. You'll be the victim whatever happens, the representatives won't think any of this is your fault.”

They breathed in deeply.

“I hope so.”

“I’m going to get Saia, now.”

“Have the representatives told you everything? About…”

Saia listened intently, but they didn't add anything else, because Hilon was already nodding.

“I know all the procedures. And I know she might be listening to us right now, so I won't say more.”

“Be careful, she…”

They trailed off, then shook their head.

“Just be careful. She's more powerful than she seems.”

Hilon's smile became softer.

“Don't worry. Get a bit of rest, if you can.”

She left the room and walked down the corridor, toward Saia's room. She checked the contents of her bag one last time: the diary in a bottle, her old clothes and some spare ones, two clean tunics of her size, Rabam's wooden owlet and little else. She opened the door before Hilon could reach the end of the corridor. She stopped in her tracks, then smiled with her lips.

“Hi, Saia. I'm sorry we didn't have a chance to talk, yesterday.”

Saia stepped out of the room.

“What do you need me for?” she asked.

“I will explain everything once we're at the factory.”

She turned to leave, glancing over her shoulder as if to invite Saia to follow her. She did, letting her domain shrink to the size of her body. She’d spent a few days of energy just by listening to the conversation in Serit’s room, but after wasting a lot more to save Serit twice she’d gotten used to smaller expenses of viss.

Just as she was thinking about Serit, they opened the door of their room. She didn't turn her head nor stopped, but still looked at them. They only raised a cupped hand in greeting and silently watched her and Hilon leave.

Once outside, Hilon seemed to relax. Saia recognized the road they were taking as the one that led straight to the elevators. She hoped they would head to the fifth level, where she could at least inspect the area to find her shard. Then she realized it would be pointless: the birdguards could move away easily every time she approached them, and she couldn't leave without taking Aili's shard too. She could only hope they were both in the same spot, like in the monks' village, but she doubted it: the space at Iriméze wasn't limited like it was back at the mountain, they could even fly around the sky with their sprites. And once the elders of Ifse gave the representatives one of their ships, her shard could be literally anywhere.

Her viss started buzzing as she realized the gravity of the situation. She needed to act quickly, before the deal between the elders and Iriméze could be finalized.

“What do you know about how the city moves?” Hilon asked, distracting her from her thoughts.

“Nothing. Serit didn't explain and I guess I haven't thought too much about it, with everything going on.”

“Guess.”

“Patterns? Sprites? The pipes that I saw the first day?”

Hilon nodded.

“Four patterns, to be specific, traced exactly with those pipes you saw. One pattern is for generating heat, another for creating the clouds that hide the bottom of the city from the lands below. These two are fixed, we never change them. Then there are two bigger ones: one is for controlling height, the other direction, and both allow the city to fly. If one breaks the other will hopefully still work long enough for us to repair it.”

“And you power them with…”

“Sprites. A lot of them, running through the tunnels.”

They had entered the elevators' room, but instead of stepping behind one of the five passengers' queues, Hilon went left toward the wall. Once she got closer Saia noticed the gray door hidden in plain sight, only its borders distinguishing it from the walls of stone. Hilon opened it with a key and gestured for her to enter first.

There was a smaller elevator room on the other side, with just one cabin already waiting for them. A guard beside an empty desk lazily extended his hand toward them. Hilon closed the door behind herself and quickly showed him her documents. Saia entered the cabin after her, the guard actioned a mechanism, and the elevator started to descend.

“A private elevator?” Saia asked.

“Not exactly, even if so few people use this one it might as well be. No, these are for the workers and engineers that take care of the pipes. There's one dedicated for each level, more or less identical to this one. The biggest one is at the fourth level, since most of the workers come from there.”

The descent didn't last much. The cabin stopped at the beginning of a corridor. There was a door of metal to left, but Hilon ignore it, going on toward the staircase at the end of the corridor. After descending it, they found themselves in front of two guards at the side of a larger, wooden door. Both of them had their fingers inside a small bottle. Still, their eyes were vigilant as Hilon and Saia stepped closer, which meant the content of the bottles was of the acoustic kind.

Saia realized it wasn't just entertainment, but a necessity: from the other side of the door came a series of loud bangs, shouts that were alternatively alarmed or annoyed, and a screeching so loud that for an instant it covered all the other sounds. She expanded her domain a bit before stepping through the door, not knowing what to expect.

The room on the other side was bigger than any she'd ever seen: bigger than the warehouse, even than the monks' temple. It was probably as big as the field of the arena, except the walls were perfectly straight and levigated, not curving stands. There was so much movement of people and machines that she had to stop for a second to make sense of what she was seeing.

What at first sight had looked like disorganized chaos was actually a working space divided into various areas, as if they were multiple rooms without walls. The center of each area was occupied by a piece of giant pipe, sometimes more than one. Depending on the area they were working on, the workers removed rust from the metal, cleaned the surface from bird feces, or joined multiple pipes together. A huge cauldron was hanging from a chain attached to the roof. The workers around it kept it in place with long poles, so that it could pour a continuous stream of red-hot melted metal into a vertical structure that looked like a cylinder. Saia couldn't figure out what it was until she expanded her domain and saw the inside: a massive mold to create a new section of tube.

Hilon expertly guided her through the various areas, following an invisible corridor that managed not to cross anyone's path. She noticed there were some humans here and there, but most of the workers were shilvé.

Once they had finally crossed the room, Hilon led her through one of the multiple doors on the other side, noticeably smaller than the entrance. The staircase behind it was extremely narrow, pressed against the wall to the left. There wasn't anything on the right side beside a handrail. The floor, made of carved stone as well, started half a towerlength below. It wasn't a proper room as much as a chamber that was rectangular in shape, except for the wall to the right of the staircase. It curved to accommodate the shape of a tunnel identical to the ones that were being created and fixed in the previous room, the ones she'd seen while ascending from the mountain to Iriméze. The tunnel was longer than the room, continuing past two holes just big enough to contain it toward what she imagined was the external part of the city.

A crowd of people was amassed next to the metal structure. She was surprised by those brown or black or blonde hair, to the point it took her a second to realize that nearly all of them were humans. A large window of thick glass opened in the section of pipe in front of them, bolted to the metal through a sturdy frame. Knobs of brass were jotting out of the glass at apparently irregular intervals. Each person was grabbing two of them, sometimes squatting or standing on tip-toes to reach them. On the other side of the glass, the knobs thinned until they became spikes.

A movement captured Saia's attention: four shilvé guards were standing next to the wall at the bottom of the stairs. They had straightened suddenly in seeing Hilon's approach, and now they were greeting her with two cupped hands, the tridents tucked between arm and torso.

“How long until the next arrival?” Hilon asked them.

“You're lucky engineer, it should only be…” A guard took out a pocket clock with a shiny quadrant, probably powered by a sprite. “A couple of minutes at most.”

Those words prompted the other guards to step away from the wall and approach the group of humans. They stood a few steps behind them, observing the scene. The fourth guard put away the clock and joined them.

Saia used those two minutes to observe the room, wondering whether her new task had anything to do with that place. A faint light started to spread from the right side of the big window. It intensified and became fog, made of sparse tendrils at first, then a mass of light so intense Saia couldn't figure out what kind of animal that sprite was supposed to resemble. Then the mass divided into smaller forms, vaguely independent but still attached to each other. They clustered around the knobs, at least ten for each if not more.

“Push,” the guards ordered almost as one.

Saia expanded her domain until she could see the people's viss flowing out of their bodies and into the knobs, where the sprites could absorb it. The guard with the clock kept checking it while her colleagues observed the scene.

“Stop!” she yelled at one point, the other ones repeating her order soon after.

The workers left the knobs, standing normally when they've been squatting or straining. The sprites hovered in front of the window, extracting every speck of viss left on the spikes, then one of them started flying at full speed in the opposite direction from where they'd come. The rest immediately followed.

“These sprites are the ones that couldn't be trained,” Hilon explained in the meantime. “We keep them in separate groups to make sure that one of them is always running even if something happens to the others, like a change of direction or some sprites cannibalizing each other.”

“That can happen?”

“Yes, if we don't feed them enough. Which is more complicated than it seems, because we never feed them fully, or they would stop running.”

“And what do you do if they change direction?”

“We have shutters that can be lowered to block their way and force them to go back. We also have several feeding stations like this one scattered all along the pattern, positioned in a way that ensures the closest one is always reachable by going in the direction we want. Sprites, especially if not trained, are simple creatures: they'll always go toward the nearest cluster of viss they can eat, be it a trace somebody left on a surface or another sprite.”

Saia thought they reminded her of sea snakes.

After the sprites had left, the workers stretched and exchanged a few words with each other. The guard with the clock kept staring at it, and after another two minutes she yelled: “In position!”

The people grabbed the knobs again, changing place with each other. After a bit more time, another group of sprites arrived, ate, and left.

The scene repeated three more times, to the point Saia was starting to fear it would keep going for the rest of the day. Fortunately, the workers stepped away from the tunnel after the fifth group of sprites had left. Most of them turned to observe the guards or talk to each other, and that allowed them to notice Saia.

She could read the surprise on their faces even better than in their viss. They started murmuring among themselves, so she expanded her domain to listen.

“… new woman? I thought our turns were full.”

“Maybe someone will be laid off.”

They started whispering names, trying to figure out which one of their colleagues was most likely to be fired. Saia realized they thought she was going to join them. It was a possibility: maybe Hilon wanted her to feed the sprites, much as these people were doing.

A short creaking sound accompanied the opening of a door in the wall, barely distinguishable from the rest much as the door to the private elevator was. The guards stood on either side of it, watching the prisoners file in front of them and down the tunnel on the other side. It was extremely narrow, to the point only a person could pass at a time, with walls so rough there were still traces of the digging. It was also completely dark, if not for a bright spot just over the entrance: four rows of lanterns were hanging from as many hooks in the wall. Each worker took one of them before walking on along the tunnel. Once they were all in, the guards followed, closing the door behind themselves.

“Where are they going?” Saia asked.

“To the next feeding station. That path,” Hilon pointed at the door. “Is a lot shorter than the one the sprites take. They'll be in place to feed them as soon as they arrive.”

“So they keep doing that the whole time? Back and forth between these windows?”

“Feeding stations. And yes, that's their job.”

Saia tried to imagine how it felt like: waiting for the sprites to arrive, feeding them with her own viss five times, going back through the tunnel, waiting again, feeding the sprites, entering the tunnel...

“The whole day?” she asked, letting her disbelief strain her voice.

“No, they follow two turns of four hours with one hour of break in between to eat. They have a room for that, maybe I'll show you later. And they can rest while waiting for the sprites.”

“And the guards?”

“Well, they're there to make sure they actually work. If they stopped, the whole city would start to fall down, we can't afford that to happen.”

Saia looked at the closed door. The room was so dull that she couldn't imagine spending there more than a few minutes.

“Why are they doing... I mean, what do they get in exchange for that?”

“Five hundred breaths a month.”

Saia recognized the colloquial name for Iriméze’s currency, but she had no idea how much that actually was. She was about to ask the amount in vissins, but it was unlikely Hilon or anyone else in the world knew how to make that conversion. It didn't matter anyways, since the lives of the people at Iriméze were completely different from the mountain's inhabitants'.

“Is that a lot?” she asked.

Hilon shrugged.

“It's enough for such unskilled labour, considering there's a crowd of people on the fourth level who could replace them in an instant.”

Saia vaguely remembered Serit mentioning that the people living there were not citizens and could change their status by working.

“Can they become citizens by doing this?”

Hilon produced a light smile.

“Of course. Usually we require twenty years of service before they and their immediate families can get the documents, but there are benefits that shorten that amount. Like multiple adults in a family working, for example.”

Saia tried to imagine twenty years of doing that job. She couldn't, but she knew exactly how twenty years looked in terms of viss expended. She'd spent more than that just by existing at Iriméze and helping Serit. Those workers would have spilt the same amount going back and forth and feeding the sprites, trapped down there much as she was. It had to be taxing on the body, since she hadn’t seen nearly as many humans around the city as the ones that should have joined it in the centuries from its creation.

“Why am I here?” she asked, fearing the answer.

“I just need you to know how the whole system works, otherwise you won't fully understand your role. Follow me, please.”

She started climbing the stairs. Despite the chaos of the factory, Saia felt better when the door closed behind her back and she was again immersed in the noise.

“Right there,” Hilon said, pointing at a door opening on the wall to the right.

Behind it there was a corridor similar to the one on the first floor of the warehouse, except for the fact the walls were of stone and painted in white. Each door on either side had a metal label on it, names engraved vertically with the Shilizé alphabet. She was surprised to find Serit's name. She expanded her domain to look at the other side, but it only contained a long table and a cabinet. Only some of the other rooms were occupied by other engineers, most of them reading some notes or sipping from a fuming cup. Their offices were full of story-bottles and notes scattered everywhere, and a couple of times even some strange machinery.

Hilon stopped in front of the door at the very end of the corridor. The handle was wrapped by a bright red cloth and a paper nailed to the wood recited: 'private'. Hilon opened it with another key.

The room on the other side was fairly big, at least half of the monks' temple in length. The wall opposite the door wasn't made of stone, but glass, not straight like the others but curving to form a half-dome. Pieces of sky were visible on the other side, the rest hidden by a curtain of thick clouds, their foggy tendrils covering the glass with droplets of water.

“Impressive, right?” Hilon said, pointing at it. “But you can only see well if we deactivate the pattern that generates clouds. We’ll need to rearrange it, eventually.”

The room was mostly empty, except for a table and a cabinet in the farthest corner, a lantern bolted to the roof, and a series of half-circles of levers that jutted out from the floor. A chair was positioned inside each half-circle. Saia stopped in front of the closest one to examine them better. The handles were made of shining brass, with a label engraved at the top: 'shutter system A1', 'shutter system B10', '30 tilt left'.

She looked at Hilon, waiting for an explanation.

“Right now,” she began, “The movement of the city is controlled through various groups of workers assigned to different mechanisms. For example, let's say one group of sprites decides to change direction: we'd notify the closest group assigned to the shutters to close them, in order to force the sprites to turn around.”

She put a hand on top of a lever, passing her fingers on the label.

“This requires a lot of communication and planning. If we want to change the route, for example, we have to study the charts and notify the various groups at least one day in advance, so that they're ready to activate the mechanisms at the right time and in the right order. Which means that if a sudden problem arises, we can't act quickly enough to move the city out of the way. Not to mention the waste of time, energy and manpower.”

She paced between the groups of levers, approaching the half-dome of glass.

“So I, Serit and some of our colleagues started to work on a system to take all of the decisions and activate all of those mechanisms from the same room. This one.”

“And the representatives didn't know about this?” Saia asked, thinking of how even leaving the city required their approval.

Hilon smiled.

“We asked Héshe and she gave her approval. She only pretended not to know about this project yesterday.”

“Why?”

Hilon shrugged.

“To take the merit once it was completed and working, probably. Or maybe she saw how important this project was and decided it was worth the risk of keeping it a secret until it was ready. It doesn't matter, the important thing is that we could start the construction of this room. But we found a problem that we absolutely didn't have the solution to, up to this day.”

She looked at Saia with smiling eyes, as if she expected her to be happy in being called a 'solution' for the problems of her kidnappers.

“Which problem?” she asked, voice low to make clear that she didn't appreciate her attitude.

“Viss, as usual. This system requires an enormous amount of energy, and we can't use the sprites for reasons that you'll understand once I'll enter into details on how it all works. We'll test it by having you powering it, and once we're sure it works, this will be your main occupation.”

Again that cheerful expression, as if she wasn't aware she was talking to a prisoner. Saia grabbed a pommel labeled '100 lowering south-east', which she imagined was a distance and a direction.

“So I'll have to move these levers…”

“They're not levers,” Hilon interjected. “They're rods, and you need to channel viss into them.”

Saia applied a slight pressure, but the rod didn't budge. She nodded.

“I’ll power them, and the city will move in that direction, or the shutters will lower and so on?”

Hilon nodded.

“That's the idea, provided it works. We never had enough viss to test it on such a large scale. But if it does, we won’t need to keep five groups of sprites anymore. We can lower them to three without fearing an incident for lack of communication.”

“I don't understand why you trust me so much. The only thing I want is to go home, and you just gave me the power to do that.”

Hilon sighed, as if Saia had just spoiled her fun by saying that.

“The old system will keep working along with the new one, of course. Even once this one will be used as our main way of controlling Iriméze's movements, we'll make sure the mechanisms can be always actioned manually. If you cause any change we didn't approve, we'll deactivate you permanently and go back to using the old system.”

Saia let go of the rod.

“What happens if the city falls?”

“There's no way you can achieve that without us noticing well in advance.”

“I’m just curious.”

Hilon looked outside, propping a shoulder against the glass.

"Well, it has happened in the past. Whole cities fell out of the sky, either because their pipes were badly damaged or because an internal conflict killed too many of the engineers who knew how to take care of the mechanisms. The inhabitants became éshan once their city fell past the rain threshold. Only about half of them reformed, scattered across the other cities.”

“The humans rained too?” Saia asked with as much sarcasm as she could muster.

Hilon looked at her, slightly bewildered. Her expression was admission enough she hadn't thought about that.

“No, of course. The ones living inside the cities died on impact, and in two cases the city fell on top of human settlements, destroying them too.”

Saia thought of all the people living on the fourth level. Messing with the mechanisms that moved the city was not an option. She felt even more trapped than she'd been before.