Tamsin Rooke had not slept, which was a skill she had developed years ago and did not enjoy.

She sat at the little fold-down desk in her cabin at half past four in the morning with a mug of coffee going cold between her palms and the chart rolled up in its leather tube at her elbow, and she did what she always did when her mind refused to settle. She made a list.

One. The insurers wanted a licensed deep-water pilot on the manifest before the Marrow Lark could take a single call this season.

Two. Her last pilot, a cheerful and entirely competent woman named Dell Warrick, had been taken off the roster by a loose crate and a very bad landing.

Three. Venn Ferries had been sniffing around the Lark like a gull around a dropped sandwich for the better part of a year.

Four. Ila Sorrel was asleep in a bunk three feet from the wall behind Tamsin's head.

She crossed out the last one with a vicious little slash of the pencil, then looked at it, and had to admit that crossing it out did not make it untrue.

Ila had arrived at ten to six the previous evening with her canvas bag and her carefully blank expression, exactly as promised, and Tamsin had pointed her down the starboard passage to the little cubby that had been a chart store until four years ago. Ila had said "Thank you" in a voice like folded paper. She had not said anything else. At eight she had gone to bed, or at any rate had closed her door, and for the next nine hours Tamsin had lain awake listening to the small noises of a person trying very hard not to make any.

She knew those noises. She knew the particular rhythm of Ila's breathing when she was awake and pretending otherwise. It was a ridiculous thing to know. It was a seven-year-old fact, an artifact, like a coin from a country that had stopped existing. And yet it came back to her whole, between one heartbeat and the next, and lay down in her chest like it had never been away.

"Stop it," Tamsin told the ceiling.

The ceiling, unhelpful as ever, said nothing.

She set down the mug and slid the chart out of its tube, because she had been avoiding it for hours and avoiding things had never once worked for her.

It lay across the desk as pale and blank as it had always been. A cracked, brown-edged sheet of heavy paper about the size of a bath towel, creased from four generations of rolling, faintly smelling of old tobacco and salt. There was nothing on it. There was nothing on it at all. She had unrolled it thousands of times in the five years since her father died, and for four and a half of those years it had stayed as stubbornly empty as a field of snow.

Last night, on the aft deck, it had drawn a line.

She had not imagined it. She would have given a great deal to have imagined it. A single thread of ink, gold in the center and teal at the edges, rising from the blank paper like frost across a window, curling once and then pointing straight at the shadows behind the crab pots on the south dock. At a figure who thought she was being invisible and was, in fact, about as invisible as a lighthouse.

Tamsin had pretended not to see her. It was the only dignified option available. She had stared into the dark for a count of ten, long enough to be sure of what she was looking at, and then she had gone below and put the chart away and lain in her bunk with her heart beating a staccato against the mattress.

It was a coincidence, she told herself now, in the plain gray hour before dawn. Old paper, new weather. A trick of the lamplight.

The chart lay unmoving under her hand and did not argue, and she knew perfectly well that it was lying by omission.

* * * By six o'clock the Marrow Lark was awake and stinking of burned toast.

Odo had commandeered the galley, which meant that the entire boat could smell fried bread and strong tea, and Juno was sitting on the engine-room stairs eating an egg sandwich with the hunted expression of a boy who had been told to behave. The morning was cold and gray and clear, with a long band of orange along the eastern edge of the sky, and the harbor smelled the way it always did, of kelp and diesel and rain waiting to happen.

Tamsin stood in the wheelhouse with a clipboard and a pen, because paperwork was a sensible kind of armor, and watched the dock through the salt-streaked glass.

At five fifty-eight, Ila Sorrel walked up the gangway.

She was dressed for weather in a sage-green waterproof jacket, dark trousers, and sturdy boots that looked like they had been polished by someone who did not know what else to do with her hands. Her hair, dark brown and wavy, just past her chin, had been tied back in a short knot that was already losing the argument with the wind. She carried her canvas bag in front of her with both hands, like a shield.

She looked thinner than she had yesterday. Tamsin hated that she noticed.

"Morning," Ila said at the wheelhouse door.

"Terms," Tamsin said, and handed her a single sheet of paper.

It was one of her better efforts. She had written it by hand at three in the morning, in the dark, with a flashlight in her teeth, and she had not allowed herself to think too hard about the fact that she was making lists of rules for a woman she had once let braid her hair. The paper was headed, in firm block capitals, TERMS OF PASSAGE, and below that sat twelve numbered clauses in the same flat, businesslike print.

Ila read them.

Tamsin watched her read. She told herself she was watching for objections. She was in fact watching the small movements of Ila's face, the faint pull at the corner of her mouth at clause four, the minute lift of her eyebrow at clause nine. It was like watching someone read a letter in a language you had once spoken fluently.

"One," Ila read, under her breath. "Obey the captain. Two, no unauthorized contact with the cargo. Three, no use of the galley after nine unless on watch. Four, no touching the captain's personal effects." Her voice was dry. "That's very comprehensive."

"I like to be clear."

"Six, no discussion of events prior to this contract." Ila paused. "Seven, no discussion of events prior to this contract, including implications. Eight, see seven."

"I thought it needed emphasis."

"It has emphasis." Ila's mouth twitched again, the faintest ghost of what might have been, in another life, a smile. She suppressed it before it arrived. "Twelve, the Marrow Lark does not leave anyone behind."

Tamsin felt the words land in the quiet space between them. She had written that one last, at three fifteen, and she had stared at it for a very long time before she decided to leave it in. It was not a clause. It was a rule of the sea, older than the boat, older than her father. It was also a very small cruelty, and she knew that.

Ila folded the paper along the creases and tucked it into her inside pocket without comment.

"Understood," she said.

"Sign it."

"I wasn't aware this part was part of the contract."

"It's a courtesy. A written receipt." Tamsin held out the pen. "I'd hate for there to be a misunderstanding."

Ila took the pen. Her fingers, brushing Tamsin's, were icy, and there was a barely visible tremor in them that made the loops of her signature wobble. She signed Ila Sorrel across the bottom of the sheet and handed back the pen too quickly, as if she were afraid of leaving it where it could be noticed.

Tamsin looked at the shaking signature and then at the woman who had produced it. There was a gray shadow under each of Ila's eyes. Her cheekbones stood out more sharply than they should. She looked, Tamsin realized with an uncomfortable twist of her stomach, like a person who had been carrying something very heavy for a very long time and had forgotten how to put it down.

None of your business, she told herself. Not any more.

"Right," Tamsin said briskly. "Test run. Shallow water, inside the breakwater. I want to see how you handle her."

* * * The Marrow Lark did not handle like a ferry.

Tamsin had known this when she hired a series of pilots over the years, and had spent a fair amount of time explaining it to each of them. A ferry was built to be gentle. A salvage tug was built to haul, and haul meant mass, and mass meant that the boat had opinions. She wallowed in a quartering sea. She resisted her rudder. She had a way of building momentum and then, quite suddenly, finding she could not stop, and an inattentive pilot could find themselves fifty yards beyond where they had intended to be with a very expensive set of pilings looming ahead.

They went out under a clean, thin morning with the sun just breaking over the rooftops of the town. Odo took the engine room, Juno took the bow line, and Tamsin took the chair at the back of the wheelhouse, a battered swivel seat bolted to the deck. Ila stood at the wheel.

For the first ten minutes, she did everything correctly.

That was the strange thing. Tamsin watched with a critic's eye and found nothing to fault. Ila's hands on the wheel were light and respectful. Her course was clean. She anticipated the Lark's lag with a pilot's patience, easing the helm over a good three seconds before she needed to, and she brought the tug around the end of the breakwater in a smooth, wide arc that would have earned praise from any examiner in the country.

She also glanced down.

It was a tiny movement, a flicker of the eyes, perhaps half a second every forty seconds or so. Down at the console, at the little glowing tablet that sat beside the compass. Then up at the horizon. Then down again.

Tamsin knew what a pilot with the Pull looked like at the wheel. She had known one intimately. A pilot with the Pull did not look down. A pilot with the Pull stood with her head up and her eyes half-lidded, her whole body tuned to something nobody else could hear, correcting by feel with the unconscious ease of a woman reaching for a glass of water in the dark. Ila had been like that at nineteen. Ila had stood at the bow of her father's tug and turned them through a curtain of fog, laughing, with her eyes closed.

This Ila looked at a screen.

"You're using the tablet," Tamsin said.

She had not meant to say it aloud. The words came out calm and flat and sat there in the cab like a dropped wrench.

Ila's hands did not move on the wheel. She did not turn her head.

"There's no rule against it."

"No."

"The insurers prefer redundancy. Instrument cross-checks are standard practice."

"They are." Tamsin leaned forward in her chair, elbows on knees. "But you never needed one."

"I got older."

"You're twenty-nine."

"A woman can mature."

The tug rolled slightly on a long, glassy swell, and Ila corrected it with a movement so small that anyone but Tamsin would have missed it. Her face, reflected faintly in the spray-fogged glass, was perfectly still. The kind of still a person achieves with considerable effort.

"Ila," Tamsin said.

"Captain."

"What happened to the Pull?"

There was a silence. The engine thrummed. Somewhere below them Odo whistled tunelessly through his teeth, and up on the bow, Juno called back some cheerful nautical nonsense that neither of them heard.

"I told you," Ila said at last. "I stopped relying on it."

"That isn't how it works."

"It is for me."

It was a lie. Tamsin knew it was a lie in the same instant she knew she wanted to press it. The question sat in her mouth like a hot coal, ready to be spat. Why did you stop? What did you do? What did you give up, on that beach, in the minutes after you left me?

She had stood on the other side of that question for seven years. She had walked around it, past it, over it, through it, and she had never once looked directly into the dark behind it, because she had a very clear instinct for what lay there.

If she asked, Ila might tell her.

And Tamsin was not at all sure she could survive the answer.

"No lying on my deck," she said instead. It came out quieter than she intended. "Add it to the list. Clause thirteen."

"I haven't lied," Ila said.

"Then you won't mind it being there."

For a moment, Ila's shoulders went rigid. Her knuckles whitened on the spokes. Tamsin saw it all in the glass, the whole brief battle of a woman deciding between a dozen possible replies and choosing, with visible effort, silence. When she did speak, her voice was gentle and very tired.

"I won't mind," she said.

Tamsin sat back. Her heart was hammering. She felt like she had just walked off a ledge and found, to her great irritation, that there was a floor.

* * * They tied up at half past nine. Ila docked the Lark with a precision that earned a low whistle from Odo, who had come up on deck in time to watch the final approach, and who stood by the rail with his cap pushed back and his oil-stained hands in his pockets.

"Fine landing," he said gruffly.

"Thank you," Ila said.

"Better than Dell's."

"Dell isn't here," Tamsin said.

"I'm only saying." Odo winked at her, and Tamsin glared at him, and he went below whistling.

Juno was already waiting at the gangway, holding three paper cups of tea in a cardboard tray and radiating hope. He gave one to Ila, one to Tamsin, and kept the third for himself, and said, "So. Did we pass?"

"She passed," Tamsin said.

"Nobody asked about me, did they? I mean the bow. The bow was great."

"The bow was adequate."

"That's high praise from the captain," Juno told Ila confidentially. "Adequate. I framed it. Not the word, obviously. The feeling."

Ila's laugh was a short startled thing. She caught it in her hand like a bird and looked, for an instant, so purely amazed at herself that Tamsin had to look away.

It was the laugh. It was exactly the laugh. She had forgotten how it went up at the end, a small surprised hitch, like a stair that wasn't there.

You are a professional, Tamsin told herself fiercely. You are a captain with a boat and a crew and a mortgage on the whole damn thing. You will not be undone by a hiccup.

"Cabin," she said, turning abruptly toward the stairs. "I need to log the run."

"Of course," Ila said.

Tamsin's boots rang against the steel treads. She went down into the narrow passage that ran between the galley and the sleeping quarters, a low-ceilinged corridor lined with riveted panels and the smell of old paint and diesel, and she heard Ila come down behind her, a few paces back, her tread soft on the metal.

The corridor was not wide. Two people could pass in it if they turned sideways. At the far end, on the right, was the door to Tamsin's cabin, a plain gray door with a brass handle and a little hand-lettered sign that said CAPTAIN in letters her father had painted, years ago, with a very steady hand.

She had reached for the handle when behind her, Ila stopped.

It was a small sound. A pause in the footsteps. A catch of breath.

Tamsin turned.

Ila stood in the passage with one hand half raised toward the wall, as if to steady herself, and her face had lost some of its color. She was looking, not at Tamsin, but at the door. At the plain gray wood and the brass handle and the hand-lettered sign.

And through the wood, faint as a pulse, came a sound Tamsin had never heard in her life.

A low, sweet, vibrating hum.

It was the chart. She knew it at once, the way you know your own name in a crowd. It lay in its tube on the desk behind that door, silent and blank, and it was humming, a sound halfway between a bell and a held breath, a sound that rose and fell with the rhythm of someone drawing in air.

Ila's lips parted.

"Do you hear that?" she whispered.

"No," said Tamsin.

It was a lie. It was the second one of the morning. She felt it leave her mouth and could not call it back.

The hum swelled, thin and shivering. Neither of them moved. In the cramped dim of the passage, with the brass handle cool beneath her fingers and Ila's eyes huge and wary and fixed on her, Tamsin felt something she had not felt in seven years. A small bright thread pulling tight between her ribs, as if the whole sea had inhaled and was waiting.

Then Odo's voice boomed down the stairwell, "Captain! Radio!" and the hum cut off like a snapped string.

* * * The radio in the wheelhouse was a battered old thing with a cracked dial and a speaker that tended to crackle in the middle of vowels, but it still picked up the Tidewatch broadcast with perfect clarity. They stood around it in a half circle, the four of them, Odo with his cap in his hands and Juno wide-eyed, and Tamsin with her arms folded and her pulse not yet quite calm.

"...repeat, Tidewatch advisory for the Saltwick coast," said a flat official voice. "Surge indicators from the outer buoy array are now confirmed. A major tidal event is projected within the current Open Tide season. All vessels licensed for Drift operations are advised that conditions may support the surfacing of Old Harrow. Vessels without deep-water endorsements are urged to remain inside the breakwater. This is not a drill. Repeat, this is not a drill."

The voice faded into static. Nobody spoke.

"Well," Odo said eventually. "That's that."

"Old Harrow." Juno breathed the name as though it were a spell. "It's really going to rise. The real one. The island nobody's seen in fifty years."

"Don't get excited," Tamsin said. "Last time it came up, a third of the Saltwick fleet didn't come home."

"But the salvage," Juno said. "Captain, the salvage rights alone. Venn will be on it like a seagull on a chip."

"Venn can have it," Tamsin said, with more bitterness than she meant to show. "I'm not in the habit of planning my season around fairy stories."

"It's not a fairy story if it's on the radio."

"Juno."

"Sorry, Captain."

Tamsin turned, to give the room a reassuring glare, and found herself facing Ila instead.

Ila had gone white. Not pale, not tense, but a deep, bloodless white, the color of paper, with her lips pressed together and her eyes fixed on the radio as though it had struck her. The paper cup of tea in her hand had begun to tilt, a slow brown stream running over her fingers, and she did not seem to notice. Her thumb, on the other hand, was working the brass ring around and around, around and around, in an obsessive, tiny, frantic circle.

She looked up and met Tamsin's eyes.

For one unguarded second Tamsin saw something raw and naked and utterly terrified there, a flash of something so large that it could not possibly be about a radio broadcast. A deadline. A debt. Something that had been waiting for a very long time and had just, with a single announcement, come due.

Then the shutters came down, and Ila said, in a perfectly steady voice, "Excuse me. I think I spilled my tea."

She set the cup down on the console. She left the wheelhouse. Her boots rang on the stairs, steady and slow, all the way down.

Nobody said anything for a long moment.

"She's not well," Juno said at last, uncertainly. "Is she? She doesn't look well."

"She's fine," said Tamsin.

It was her third lie of the morning. It tasted the worst of all.

She turned to the window. Far out beyond the end of the breakwater, the sea lay flat and bright under the rising sun, as innocent as a sheet of glass, and nothing in it, nothing at all, gave any hint of what was waiting under the surface.

She thought of the chart, humming behind its gray door.

She thought of the thread of gold ink that had pointed, last night, straight into the dark where Ila had been standing.

Whatever Ila Sorrel had come back to Saltwick for, Tamsin realized with a slow, cold certainty, it had very little to do with a contract. And when the truth finally surfaced, as truth did, as islands did, as everything the tide had ever tried to bury inevitably did, Tamsin was not at all sure she wanted to be standing on the shore.

She pulled out her pen, and without quite deciding to, wrote beneath her list in a small, careful hand:

Five. Find out what she's hiding.

Then, after a moment, and with a fierce little stab that tore the paper:

Six. Do not care.