For four days after the incident in the cabin, Tamsin and Ila were scrupulously, devastatingly polite.

It was a feat of coordination that would have impressed a ballet company. They passed each other in the narrow companionway with a murmured "Excuse me" and a delicate, simultaneous flattening of shoulders against the wall. They ate meals at opposite ends of the galley table, with Juno and Odo seated between them like referees. They took turns at the wheel in a strict rotation, calling out course corrections in clipped, professional tones, and when their hands happened to meet over the helm, both withdrew them with the swift courtesy of people touching a hot kettle.

"Good morning, Captain."

"Good morning, Pilot."

"The surge looks steady."

"So it does."

"Would you care for the chart?"

"Thank you, no."

It was exhausting. Tamsin had never been so tired in her life. She would have preferred a fistfight. A good honest shouting match, with thrown mugs and slammed doors, would have cleared the air in an afternoon. But they had both, apparently, decided that the only safe response to a golden explosion and an accidental holding of hands was a rigid and total silence, and so they went about their business like two icebergs sharing a bathtub.

"You two," Odo said, on the fourth morning, over a plate of burnt eggs, "are driving me to drink."

"I don't know what you mean," said Tamsin.

"I mean that if one of you says 'excuse me' one more time, I shall take the nearest wrench and make it a very short season."

"We're just being professional."

"You're being ridiculous." He mopped up yolk with a piece of toast. "It's like living with a pair of cats who've been introduced at a funeral."

"Odo," said Tamsin.

"I'm only saying."

At the other end of the table, Ila had gone pink to the ears. She was looking very hard at her tea. Juno, between them, glanced from one to the other and shoveled his eggs into his mouth with great determination, as though hoping to leave before the explosion.

"Open Tide's in forty minutes," Tamsin said, rising. "Everyone to stations."

"We're going to the Shoal?" Juno said, through a mouthful.

"The Shoal."

"Is it bad?"

"It's not bad," Tamsin said. "It's complicated."

* * * Ledger Shoal rose out of a pewter dawn with a soft, rustling sound, like a thousand pages being turned.

Tamsin had been here a dozen times in her life. She had been here first with her father, when she was nine, wrapped in a life jacket that came down to her knees. She had learned the rules of it before she learned to ride a bicycle. And still, every time, she felt the hair rise on the back of her neck as the first of the great pale shapes broke the surface of the water.

It was not an island. Not quite. It was a shallow bank of silver sand, maybe half a mile long, flat as a table and a few inches deep, over which lay a thin sheet of clear water, still as glass. And scattered across it, stretching away to every horizon, were the ledgers.

There were thousands of them. Ten thousand. A hundred thousand. They floated just beneath the surface, drifting in slow lazy circles on the current, great leather-bound books and tiny paper notebooks, rolls of parchment and loose sheets of foolscap and strings of knotted rope and notched wooden tallies. Some were new. Some were so old they had begun to dissolve into pulp, their pages unfurling like sea anemones. Each one gave off a faint light, a gray-blue luminescence, and the whole shoal glittered under the dawn like a field of lamps.

"Ledgers," Juno breathed.

"Promises," Tamsin said. "Every one. That's how the Shoal remembers."

"Remembers what?"

"Everything anyone ever swore to do and didn't." She leaned on the rail beside him, hands in the pockets of her oilskin, watching the pale glow slide beneath the hull. "Every I'll call you tomorrow. Every I'll be home for supper. Every I swear I'll never leave you. They sink out here. They collect. And when the tide's right, they come up and wait for someone to claim them."

"That's horrible."

"It's honest." She glanced at him. "It's also dangerous, if you're not careful. Don't touch anything. Don't pick anything up. If you find yourself wanting to read one, step back and count to twenty."

"What happens if you read one?"

"You hear it," said Tamsin. "The whole thing. The moment it was said, in the voice that said it, with all the feeling that went with it. And you remember that you meant it, once. And you remember that you didn't do it."

Juno was silent. His face had gone a little pale.

"Right," he said. "Count to twenty."

"Good lad."

Behind them, in the doorway of the wheelhouse, Ila said nothing at all. But Tamsin felt her there, the way you feel a draft, and she did not turn around.

* * * The fisherman's name was Bram Hollis, and he had been stuck on the Shoal for six hours.

He was a stout, weathered man in his sixties, with a face like a walnut and a long dirty gray beard. His skiff, a little clinker-built boat the color of old bone, sat wedged on a hump of sand at the northern edge of the bank, and he was perched on the stern with a thermos in one hand and an expression of weary embarrassment. As the Lark drew alongside, he raised the thermos in salute.

"Morning, Captain."

"Bram." Tamsin shouted across the water, with a laugh she did not entirely feel. "I thought you swore off the Drift after the last time."

"I did. I was just checking the lobster pots."

"In the Drift."

"It's a very good spot for lobsters."

"It's a very good spot for dying, Bram."

"Nonsense," said Bram Hollis comfortably. "I've got my thermos."

They towed him free in twenty minutes. It was a simple job, simple enough that Tamsin felt the knot in her stomach begin, slightly, to loosen. A line over the bow, a gentle pull astern, a hand on the rail and a polite reminder that if he ever came out here without a license again she would personally confiscate his boat. Bram nodded and wheezed and said he understood perfectly. Odo, grumbling, helped him aboard the Lark for a cup of tea and a blanket.

It was while they were securing the skiff that Juno found his ledger.

He did not mean to. Tamsin knew that. She saw it happen out of the corner of her eye, a small bright flash of bad luck: a boy leaning over the stern to check a knot, and his bootlace trailing in the water, and a small notebook the color of a dove's wing bobbing up from the depths and fetching up against his ankle.

"Juno," she said. "Twenty."

"I'm not touching it."

"Count."

"I'm counting. One. Two." He was staring. His whole body had gone very still. "Captain, it's got my name on it."

"I know."

"It says Juno Pike." His voice had gone small. "It's got a little drawing on the cover. It's a boat."

"I know. Back away."

"Three. Four." He was not counting. His hand had already begun to reach. "I only wanted to see. It's mine. It's my own, I'm allowed, aren't I? It's my own promise."

"Juno."

He picked it up.

Tamsin crossed the deck in four long strides, but it was too late. The notebook opened in his hands like a flower, a small gray bloom of light, and out of it, soft and sweet and unmistakably young, came a voice.

I'll come home at Christmas, Mum. I swear. I'll come and I'll stay the whole week, and we'll do the crossword like we used to. Don't cry. I'll be there. Promise.

The voice was his. It was nineteen-year-old Juno, bright and eager, as he must have sounded on a train platform on a cold December evening three years ago, with a duffel bag and a red nose and a wide hopeful grin. It filled the air of the deck like a bell.

The real Juno stood perfectly still, with the open notebook in his hands.

"I didn't go," he said.

"Juno."

"There was a call. A salvage run. We had a boat in trouble off the Narrows, and I thought, I'll go next week. And then next week there was another. And then." He swallowed. "It was Christmas and I was on a boat. And she waited. She waited all day, Captain. She made the whole dinner."

"I know."

"I forgot. I wasn't even trying not to. I just forgot."

"It's all right."

"It isn't," said Juno, and began to cry.

She took the notebook out of his hands, very gently, and closed it. The voice stopped. She tucked it into her pocket and put an arm around his shoulders, and he turned his face into her jacket and shook, and she patted his back and murmured things she did not quite hear herself say.

Behind her, a single quiet breath.

She looked up.

Ila was standing at the stern rail. Her face was perfectly white. She had one hand over her mouth, and the other pressed against her stomach, as if she had been struck there, and she was staring at something in the water.

A small bright thing, floating on the surface, half a yard from the hull. It gleamed in the pale light like a coin. It was a ring.

* * * It was a cheap one.

Tamsin could see that even from where she stood. Tin, or pewter, a slim twisted band with a small, clumsy flower stamped into the top, the sort of trinket sold at harbor fairs for a few coins to children and lovers. The tin had tarnished to a dull silver gray. A loop of pale blue ribbon was threaded through it, frayed at the ends.

It bobbed gently in the swell, turning, turning, and as it turned it caught the light, and the light caught something engraved on the inside of the band, three tiny letters.

She knew it.

She did not know how she knew it. Her mind had gone entirely blank. But her body knew, and her body moved, drifting across the deck and down to her knees at the rail, and her hand reached out of its own accord and plucked the ring out of the water like a fish from a stream.

"Tam," Ila said. Her voice was hoarse. "Don't."

"It's a ledger."

"It's. Please, Tam. It isn't yours."

"It's got my name on it."

It did. Not the letters she had thought. The engraving on the inside of the band, worn almost smooth, read T.R., in a clumsy, laborious hand. As though someone had done it with a pin. As though a very young person had sat for hours with a bent needle and a bit of tin, and had taken great pains to get the shapes of the letters exactly right.

"I bought it at the Pennywhistle fair," said Ila. She sounded like she was speaking from the bottom of a well. "The summer we turned twenty-one. It was fifty pence. I couldn't afford a real one."

"I never saw it."

"I never gave it to you."

"Why not?"

"Because I was saving it," Ila whispered. "For the right time."

The ring was cold in Tamsin's palm. Cold, and light as a leaf. She turned it over and the blue ribbon trailed across her wrist like a fingertip, and the surface of the tin lit up from within, soft and silvery.

She knew what was coming. She did not want it. She felt it crouch at the back of her mind like a cat about to spring.

Don't, she told herself. Put it down. Count to twenty.

She heard it anyway.

I'll come back for you.

The voice was young. Not the voice of a girl of nineteen, bright and bold and full of herself, but something quieter and more fragile. A twenty-two-year-old voice, rough with cold and fear, trembling at the edges, and underneath it, as clear as a struck note, a naked, desperate sincerity.

I'll come back for you, Tam. I swear. Wait for me. It won't be long. I swear on everything. Just wait.

It was the voice of a woman standing on a shingle beach in the dark, with a lantern in her hand and the sea at her back. A woman who had made a promise. A woman who meant it with every fiber of her being.

And who had not kept it.

* * * Tamsin did not remember throwing the ring.

She remembered the sound, a sudden hard crack, like a gun going off. She remembered the swing of her arm and the flash of tin in the air, spinning end over end, and the little ribbon fluttering behind it like a tail. And then the ring was in the water, and the water closed over it with a small clean plop, and the light in the ledger went out.

Silence.

Odo had stopped with a mug of tea halfway to Bram Hollis. Juno had lifted his face from her shoulder, his eyes huge and wet. Out on the Shoal, ten thousand pale lamps drifted in slow circles, and a thin gray wind stirred the surface of the water, and the whole wide dawn seemed to be holding its breath.

Ila stood at the rail with her arms wrapped around herself.

She was shaking. Her face was wet, though she did not seem to know it. She was looking at the place where the ring had gone down, and her lips were moving, and Tamsin realized, with a lurch, that she was counting. One. Two. Three. As if she, too, were waiting for it to stop.

"Say something," Tamsin said.

Her voice came out like a stranger's.

"I don't know what to say."

"Say anything."

"I'm sorry," Ila said, and put a hand to her throat. "I'm so sorry. I wanted to. I swear to you, I wanted to come back."

"But you didn't."

"I couldn't."

"Couldn't or wouldn't?"

"Tamsin."

"I'm asking you a question." Her hands were shaking. She pressed them hard against her thighs. She was aware of an enormous, hollow, roaring anger, the old anger, the one she had thought she'd exhausted years ago, rising in her like a flood tide. It filled her to the top of her skull. "Seven years. I waited seven years. Do you know what I did the first winter? I stood on the south breakwater every night for five months. Every night. I thought, she's just late. She's only delayed. And then the spring came, and I stopped."

"I know."

"You don't know."

"Tam."

"Don't call me that." Her voice cracked on the last word. "You don't get to."

Ila flinched as if she had been slapped.

Something dark moved behind her eyes. A deep struggling shadow, as though a great weight were pressing on her from within, trying to rise to the surface. Her mouth worked. Her hand tightened on her throat, and for a moment she looked less like an angry woman than a drowning one. A pale, silent creature fighting to speak, and unable to make a sound.

Tamsin watched.

She watched Ila's lips shape a word, and fail, and shape it again, and fail. She watched a muscle jump in her jaw, and her fingers go white against her collarbone, and her breath come in short desperate gasps. She watched the helpless, wordless agony in her face. And a small cold voice somewhere at the back of her mind said, with terrible clarity:

It isn't that she won't tell you.

It's that she can't.

The thought hung in the air like a bell.

Tamsin took a step backward. She had not meant to. She found the rail against her spine, and gripped it, and did not know what she was feeling. It was anger, still. It was grief. But underneath both, rising like an island from a dark sea, was something stranger and far more dangerous. A question. A terrible, tender, unwelcome question.

What happened to you?

She did not ask it. She was not ready. She was nowhere near ready.

"Rope," she said instead.

It was the only word she could find.

Ila blinked at her.

"I need a line," Tamsin said, hoarse. "Over the stern. Skiff's drifting. Ila." She stopped. Swallowed. Said it again, very softly, in a voice like torn paper. "Ila. Rope."

For a moment nobody moved.

It was the first time she had spoken her name in seven years. It lay on the deck between them like a dropped cup, and neither of them could pick it up.

Then Ila's shoulders came down, very slowly. She drew a breath. She wiped her face roughly with the back of her hand, and bent, and lifted the coil of line from the deck, and her fingers, when she held it out, were trembling like leaves.

"Here," she said.

Tamsin took it.

Their hands did not touch. She made certain of it. But she felt the closeness all the same, a warm taut thread of awareness stretched between them, and she knew with a sinking heart that it was not going to loosen.

* * * They towed Bram Hollis's skiff back to Saltwick under a sky the color of tarnished silver.

Nobody talked. Even Odo, who could usually be relied on to produce a wry remark, kept his mouth shut and his eyes on the engine gauges. Bram himself, clutching his blanket, looked from face to face with the bright, alert interest of a man who had just walked in on something private.

The chart came out on the way home.

Tamsin had not meant it to. She was sitting alone in the stern with a mug of cold tea and the tin ring burned into her mind like a brand, and she heard, quite distinctly, the soft hum of the leather tube in her cabin. She went below without thinking. She unlocked the drawer with fingers that did not feel like her own. And she drew out the chart and unrolled it across the desk, and found that the empty parchment had changed again.

The orchard was still there, in the top left corner, a little cluster of silver trees. But beside it, a hand's breadth away, a second drawing had appeared. A long, shallow oval of fine pale lines, ruled in gold. Inside it, the tiny shapes of drifting books. Beneath them, written in the same slanted, looping hand, a new line of text.

Every promise is a debt.

She stared at it.

There was a movement behind her. A soft footfall in the passage. She turned, with her heart in her throat, and found Ila standing in the open door of the cabin, one hand on the frame. She had not meant to come in. That was clear. She had stopped on the threshold as though a wall had risen in front of her, and she was looking at the chart with an expression of yearning so naked that Tamsin's breath caught.

"May I?" Ila said.

It was a very small request. Barely a whisper.

Tamsin should have said no. She had said no a dozen times in the past week. It was the correct answer. It was the only answer that kept her safe.

"Come here," she said.

Ila crossed the cabin. She stood at Tamsin's shoulder, close enough that their sleeves brushed, and looked down at the chart. The gold light flickered across her face. Her lips moved silently over the new line, and her hand rose, almost without her volition, toward the edge of the paper.

Tamsin's hand was already there.

Their fingers touched at the margin. Just the tips. Just for an instant.

And the whole chart lit like a candle.

* * * It was Odo who broke the spell.

He had come down the stairs for a spanner, and he stopped in the passage, and he saw them. He saw the two of them bent over the desk with their hands almost touching and the gold light pouring up between them. He saw the new page. And he saw, with one long slow glance, the looping handwriting at the bottom.

He went very pale.

"That's Cormac's hand," he said, under his breath.

They both turned.

He was staring at the chart with an expression Tamsin had never seen on his face, a look of old, deep, wary dread, like a man looking at a ghost in a mirror. His eyes moved from the paper to Tamsin, and from Tamsin to Ila, and rested there, long and level and entirely without surprise.

"Odo," Tamsin said slowly. "What do you know?"

"Nothing," he said.

It was a lie. She had known him all her life, and she had never once heard him tell one. It sat badly in his mouth, like a stone.

"I know nothing at all, Captain," said Odo Fenwick. "I only wondered. If somebody might have told you about the last page."

"The last page?"

"Never mind."

"Odo."

"It's late," he said. "I'll see to the engine."

He turned and left. They heard his boots on the steel stairs, slow and heavy, and then the clang of the engine-room hatch, and then silence.

Ila's hand was still lying beside hers on the parchment, not quite touching.

"What did he mean?" she whispered. "What last page?"

Tamsin did not answer. She was looking at the chart, and the new line of ink, and the long gold thread that had begun to curl out from the edge of the Shoal toward a place she could not yet see.

Every promise is a debt.

Whatever her father had known, whatever he had left unsaid, it was waiting at the bottom of this sea like a stone at the bottom of a well. And she had a dreadful, creeping, certain feeling that the woman beside her was holding the other end of the rope.