She did not answer him that night, and he did not ask twice.

That was the first thing Suzu noticed in the morning, lying awake on the narrow bed with gray light in the cracks of the shutters: that he had let the question stand. He had simply nodded, once, as if she had given him a perfectly adequate reply, and said that the hour was late, and walked her back to her door. He had not said a word about it since. She did not know whether to be relieved or alarmed.

The bell rang for seven. She was dressed in ninety seconds, which was a school skill, and had the coat folded over her arm in two minutes more, which was not. She stood in the corridor holding it, unsure whether to wear it or leave it, and was still standing there when she heard the stairs.

"You are early," said Sael.

He was coming up from the landing below with a covered tray, and he looked, in the morning light, very slightly different. The edges of him were sharper. His hair had been combed. The coat he wore was a fresh one, pale and navy-edged and exactly like the first. It occurred to her that he probably had a rack of them somewhere, identical, in a row.

"I said eight at the quay," Suzu said. "I thought I would be early."

"It is a forty-minute passage at ebb. You would have been early by an hour."

"I like being early."

"That is a compulsion."

"It's a virtue."

"It can be both." He set the tray on a ledge and lifted the cloth. Bread, a wedge of pale cheese, a small cup of something steaming. "Eat. I will escort you. The route is not marked."

"Not marked?"

"There are stepping stones. At ebb they are above water. At flood they are not. Six of them are loose." He paused. "I know which six."

She ate, standing, with the coat over her arm. The cheese was sharp and salty and the drink was bitter and warm. When she looked up, he was watching her chew with an expression of slightly baffled interest, and he looked away at once.

"I will carry the coat," he said.

"It's yours."

"Then I may carry it."

She handed it over. Their fingers did not touch. She was almost sure she had avoided it on purpose, and she was almost sure he had too.

---

The causeway began at a small stone door on the tower's east face, and for the first ten steps it did not seem to exist.

Suzu stood at the lip of the door with her toes at the edge of the landing, and looked out at a flat green sea that stretched to the horizon with no sign of anything under it. It was bright. It was calm. There was not a ripple, not a mark, not a single rock.

"There is no path," she said.

"There is a path." Sael stepped past her, and set his foot on what looked like open water. His boot came down on stone. A thin sheet of water slid away from the sole and returned. "Follow my steps. Not my direction. My steps."

"I can't see where."

"I know. I can."

She put her foot where his foot had been, and the stone was there. Then the next. He went ahead at an even pace, not looking back, and she followed, and the sea lapped at her ankles and the light came up gold. He did not look at the water. That was what she kept noticing. He looked at the horizon, or at nothing at all, and his boots found the stones one after another with the confidence of a man crossing his own kitchen in the dark.

"How do you do that?" she called.

"I remember."

"You've done this crossing a lot."

"Four hundred and twelve times." He stepped left. "The fourth stone from here is loose. Go left of its center. Not the middle. Left."

She went left of the center. The stone wobbled and held.

"The water was a hand higher yesterday at this hour," he said, over his shoulder. "It will be two fingers lower tomorrow. The ratio changes with the moon. There are two moons. You will not have noticed the smaller."

"I didn't."

"It is the color of a tooth."

She laughed, and nearly stepped wrong, and caught herself. He had stopped. He had turned, with one boot on a stone and one hand reaching out, not to touch her but to indicate a place for her to put her weight. His eyes had gone to her face and stayed there.

"Do not laugh on the stones," Sael said. "Please."

"Sorry."

"It is not that I object." He said it too quickly, and she saw him hear it. "It is a safety matter."

"Of course."

They went on. The sun climbed. And somewhere around the two-hundredth stone, with the east quay a small brown smudge ahead of them, Suzu realized she had stopped being afraid of the water. It had happened without her permission.

---

Nana hit her at the foot of the quay steps at a dead run.

There was no other word for it. A small body with a lot of wet hair and a borrowed gray tunic slammed into Suzu's midsection hard enough to make her stagger, and two arms went around her ribs, and a muffled voice said into her blouse, "You came. You said eight and it's seven fifty-one. You came."

"I said I would."

"I know. I know you did. I just." Nana held on. "I didn't sleep."

"Neither did I." Suzu pressed her hand to the back of Nana's head, and thought, I counted. Seven forty. East quay. She is here. She is warm. She is here. "Did you eat?"

"There was porridge. Ren said it tasted like pencil erasers."

"It did," said Ren.

He was sitting on the quay wall with his knees drawn up, looking as though he had been awake since the previous afternoon, and he looked past Suzu at Sael, who had stopped three paces back with the coat over his arm. Ren's eyes went narrow. He looked, for just a second, like someone watching a stray dog approach a child.

"Good morning," said Sael.

"Is it," said Ren.

"Morning, Madam President," called Haruto, appearing around the corner of the lodging house with a cup in each hand and a small tower of pastry on his head. "Don't be alarmed. I have secured breakfast by a combination of charm and sign language. I have also secured a candle. I have used it. I assume you saw."

"I saw," said Suzu. "Three flashes."

"It was supposed to say 'we are alive.'"

"It said it."

"I was worried it said 'help, a goat.'"

She was laughing again, and this time she did not stop herself. Behind Haruto, Miyu emerged from the lodging house with a clock in pieces in her hands, a brass thing with a ring of glass beads for a face, and said without preamble, "Their tide clocks are wrong."

"Good morning, Miyu."

"They count the interval between peaks, but it drifts. Look." She held out a gear. "This drive ratio compensates for something that isn't there. Whoever built it knew the tide wasn't regular and made it run slow on purpose, but they did it for the wrong reason."

"They did it for the right reason," said Sael.

Miyu froze, gear in hand. He had spoken in his usual even voice, and every head on the quay had turned.

"The smaller moon," said Sael. "The clock was calibrated for the larger moon alone. It has been run slow to approximate both. It is an approximation. It is a poor one. I have been aware of the error for eleven years."

"You never fixed it?"

"I am not permitted to alter tower instruments."

"That's insane."

"It is regulation." His eyes did not move. "I have noted it in six consecutive reports."

"And?"

"They were filed."

Miyu looked at him for a long moment. Then, slowly, to the surprise of everyone, a grin broke across her grease-streaked face. "I like him," she announced. "Suzu. I like your guardian."

"He is not," Suzu began, and heard it, and stopped. "He's the Auditor."

"Same thing."

Haruto, behind her, made a sound like a kettle.

---

The orientation was Sael's idea, or rather, it was an Auditor's duty, and he delivered it with the air of a man performing an unpleasant surgery with great skill. They walked the district in a line, Suzu and Sael at the head, the rest following: along the east quay, over a humped stone bridge, down a street so narrow that the roofs nearly touched overhead and the water in the canal beside them was green as bottle-glass. Everywhere the Kethari moved around them without a glance. They were silent, gray, quick, elegant people, faces closed like doors, and they walked in the middle of the lane and not the sides, as though the buildings might lean in.

"This is the Office of Audit," said Sael, at a long low building with its door bolted. "It receives the registrations. It issues the entries. It is the origin of every document you will ever carry."

"Is that where you work?" asked Nana.

"I work in the tower. Rank three does not receive a desk."

"Sounds lonely," Haruto offered.

"It is efficient."

He led them on. He described the five districts, the three bells, the curfew at the second evening bell. He explained that every citizen carried a registration and every registration was reviewed once per cycle. He explained that no one in Kethari was unwatched, and that this was a courtesy, not a threat: a person who is watched is a person who is not alone. He recited it in the same flat, level cadence as everything else, and Suzu, listening, had the odd impression that the sentence had been made smooth by long handling, like a stone in a river.

"And if somebody breaks the rules?" Ren asked.

"There are corrections."

"What kind of corrections?"

"They depend on the infraction. Minor deviations are noted. Major deviations are referred upward." A pause. "Persistent deviation is recalibrated."

"Recalibrated," said Haruto. "Like a, a tune-up?"

"Yes," said Sael.

It was said so evenly that Suzu almost missed it. But his hand, the one that held the coat, had closed on the fabric, and the knuckles were pale for an instant. She saw it. She saw him see her see it.

Nobody asked anything else for the next two bridges.

"The gate," Suzu said at last. "Tell me how it works. Properly. I want the mechanism."

"I will tell you what I am permitted to tell you."

"Then tell me what you know."

He stopped on the crown of a bridge. Water ran under it in a long green gleam. Sael put one hand on the parapet and looked down into the current for several seconds, and when he spoke again, his voice had lost some of its gloss.

"The gate opens at the turn of the highest tide in each cycle. A cycle is twenty-six days. The first opening admits a wide aperture, perhaps ten minutes. The second, perhaps seven. The third, four." He paused. "Each window is narrower than the last. It is a progression. I have the historical figures. In all recorded cycles the gate has closed entirely by the fifth."

"The fifth," said Miyu, quietly.

"If the pattern holds. It is not guaranteed to hold."

Suzu had the inventory book out and was writing. Her hand was steady. Window one: nineteen days. Ten minutes. Window two: roughly forty-five days after. Seven minutes. Window three: four. Window four: unknown. Window five: closed. She underlined the last one twice, and then drew a box around the whole column, and then she looked up and found Sael watching her stylus move with his lids drawn halfway, as though he were watching a candle.

"What?" she said.

"You have written 'unknown' beside the fourth."

"It is unknown."

"I did not say it was unknown. I said I had no figure."

"That's the same thing."

"It is not." He considered it. "I do not wish to say that there is a fourth. I wish to say that I do not know."

She looked at him. There was something in his face then that she hadn't seen before, a flicker of something close to discomfort, and she thought: he does not like being asked to hope. She wrote it down in the margin, in the smallest hand she had, and never took her eyes off him while she did.

---

It was Nana's shell card that did it.

They had stopped at a canal-side rail where the road bent, and Nana had been trailing the others, her head down, her lips moving. Suzu thought she was practicing the names of the bridges. Then she saw the card between Nana's fingers, the pale shell with its etched line of script, and the girl was tracing the lines one at a time with her thumbnail.

"What does it say?" Nana asked, to no one. "It looks like I can read it. But I can't."

"It reads," said Sael, "File Nine, Entry Four. Arrival. Female. Sixteen years." He glanced down. "Subject number Nine-Four-Seven."

Nana's thumb stopped.

"Nine-Four-Seven," Sael repeated. "It is the identifier by which you will be known in the register."

"She has a name," said Suzu.

It came out sharper than she had intended, and it carried. A passing Kethari woman glanced at them and away. Haruto went still. Miyu's gear stopped turning. Ren, who had been about to say something, closed his mouth, and a look of fierce, quiet satisfaction crossed his face.

Sael turned his head.

"It is an administrative designation," he said.

"She is not a designation." Suzu stepped in front of Nana, and found, to her own surprise, that she had put out her arm. "Her name is Fujisawa Nana. She is sixteen. She likes standing waves and she hates porridge and she's been brave for about twenty hours straight, and I will not have her called a number."

The silence on the bridge was total.

Sael looked at her. Then something happened in his face that was almost impossible to describe: the stillness did not break, but it shifted, as when a sheet of ice takes a hairline crack and the whole surface turns, very faintly, to a different weight. The clear inner lid slid across his eyes. It moved slowly. It stayed.

"I have used the term for eleven years," he said.

"I know."

"No one has objected."

"I'm objecting."

He was silent for a long time. It felt as though the entire canal had stopped moving to listen. Then he turned, not to Suzu, but to the small, frozen girl behind her, and he inclined his head by a precise, formal degree.

"Fujisawa Nana," said Sael.

That was all. It was neither an apology nor an admission. It was simply her name, spoken correctly, in the voice he used for the law.

Nana blinked up at him, openmouthed. "That's me," she whispered.

"Yes," said Sael. "It is."

He straightened and went on walking, and the line followed, a little dazed. Haruto drifted up beside Suzu, and without looking at her whispered, "Madam President, I need you to know that I just saw a gray man correct himself in public and I think I may be in love."

"Shut up, Haruto."

"I'm only saying that the team has a new favorite."

"Shut up."

He did, grinning. Suzu walked on with her hands clenched at her sides and her heart doing a stupid, rapid, off-beat thing she did not have a column for. Ahead of her, Sael's back was perfectly straight. He did not turn around. But as they passed under the next arch, she saw his left hand rise, very slightly, and touch the coat over his arm, as though checking that it was still there.

---

They ended the tour at the lodging house, in the long common room with its low benches and its smell of porridge and wet wool, and Sael set a stack of shell cards on the table and went through the rest of the rules.

They could walk the district. They could not leave it. They could talk to the Kethari, though the Kethari would not reply. They could eat in the common room at three bells and at the evening bell. They were not to approach the Office of Audit. They were not to touch the waterline posts, which were calibrated to the tide and were considered public instruments. They were not to carry objects that altered water, stone, or light.

"What if we build something?" said Miyu.

"That would be a violation of clause six."

"What if it's a clock?"

"A clock does not alter water."

"Then it's fine."

"It is conditionally fine," said Sael, "provided that I am not looking at it."

Miyu beamed. Ren put his head in his hands.

Suzu wrote it all down, and then she wrote, at the bottom of the page, in letters so small they were almost invisible: guardian: fair, exact, hides a limp. She did not know why she had written it. She did not know where it had come from. But it was true, in whatever way a thing can be true that you only see by accident, and she looked at it for a while without erasing it.

When they were done, Sael rose and gathered the cards. The common room had begun to fill with the noon-bell quiet. He stood a little apart from the table, tall and straight in the dust-gold light from the window, and spoke the last of his remarks to the room at large, in the voice of a man reading a notice posted on a wall.

"Finally," he said. "The matter of attachments. Outsiders are not permitted to form binding ties within Kethari. It is the first and most strictly enforced provision of the register. I will say it once more so that it is clear." He paused. "A tie formed in this place cannot be carried out of it. It cannot survive the gate. It will be, if discovered, corrected."

Nobody said anything.

"Do you understand?" he asked.

He was looking at no one. His eyes were fixed on a spot above the heads of the group, on the whitewashed wall where a long thin crack ran upward from the floor. His voice was perfectly level. But as Suzu watched, the fingers of his left hand, the one holding the cards, began to tap against the edge of the paper. Tap, tap, tap, tap. A slow, even pulse.

He was not saying it to the room.

He was saying it to himself.