RAFE

The harbourmaster shifted two merchantmen to give us room. I did not ask him to.

I write her into the ship's books myself, in ink, so it can't be rubbed out. Kerr, I. Navigator. Of Edinburgh.

Today she corrected my chart in front of my crew.

She was right. She has always been right.

ISOBEL

The privateer who empties harbours has given me the only key to my cabin, which is frankly sinister.

It's brass, still warm from the ship's boy's pocket, and my palm is damp around it. The lock it fits is new, and it's on the inside of the door. My side.

Pinned beneath it is a card in a purser's tidy hand.

Miss Kerr may go ashore at any port, at any hour, in the captain's boat. No man aboard will ask her why.

Under that, initials slashed in like a man signing for rope. R.M.

I've been in the Caribbean since dawn. I've heard about Captain Marlowe all the way across the Atlantic, and no story ended with the lady keeping the key.

In the stories, ships see his colours and strike before he's fired a gun. Harbours empty. Grown men take up religion.

What I want, right now, is small and specific: my instruments out of their crate, and my feet on his quarterdeck before anyone decides a woman navigator was a clerical error.

What I have is a pulse in my fingertips, and a key I keep turning over as if it might confess.

The cabin is the size of a larder, which at sea is a palace. A cot, a window the size of a book, and a drafting table, new pine, standing higher than any table has a right to.

I put my hands flat on it. It meets them exactly.

I'm five foot ten. Every desk in Edinburgh has given me a crooked back since I was a girl. The shavings under this one are a week old, and I landed this morning.

The back of my neck goes hot before I've worked out why.

Beside my hands sit a bottle of ink from the shop at the foot of my own close, which does not ship across the Atlantic, and a purse: the first quarter's fee, in gold. Triple.

Something butts the backs of my knees.

It's a goat. Small, brown, bearded, with a criminal expression, and she's eating my card.

"No," I tell her. "That's a contract."

"She can't read," says a man's voice through the wall.

The bulkhead is thin pine. The voice comes through it low and unhurried, from about the height of my shoulder.

"Captain Marlowe," I say to the wall.

"Miss Kerr."

"Do you always listen at walls?"

"It's my wall."

"It's my side of it." I tug the card out of the goat. One corner's gone, and with it the word hour. "Your goat's eaten my right to leave at any hour."

"Then you may leave at any minute. I'll have it rewritten."

"Was the lock your idea, or the purser's?"

"Mine."

"Why?"

A pause.

"So you never have to wonder," he says. "Nobody comes through that door without your leave. Not my crew. Not the Navy. Not me."

Something low in me turns over and sits up.

"And the table?"

"The carpenter built it."

"To a height you guessed."

"I didn't guess."

Not one of the stories mentioned he'd be shy.

"Captain," I say, "you've just told a woman alone in a locked room that she's the one person on your ship you can't give orders to."

"Yes."

"Then here's my first. Take your goat."

Silence. Then, faint through the pine, a man trying hard not to laugh, a short whistle, and a boy at my door for the goat, who leaves with the rest of my card in her mouth.

One to me.

A sensible woman would stay below with the lock turned until she was sent for. I've been sensible all my life. It has got me a crooked back and my father's name on every chart I ever drew.

I go up.

The deck of the Reprisal is full of men who stop talking, all very busy not looking at the tall woman in the green gown with a pencil through her hair.

Aft, an old man with a white pigtail has a chart pinned to the binnacle with a marlinspike and both fists. The sailing master, laying our way out of the harbour.

I look over his shoulder. I can't help it.

The chart's an old Admiralty plate. It shows a spit of sand off the third cay, and the spit is in the wrong place.

I came in over it this morning, sounding with my own lead because I trust nobody's, and watched the water go from ink to bottle-green to the milky jade of sand under the keel. A full cable west of this.

"That shoal's wrong," I say.

The master doesn't turn round. "Is it, miss."

"By a cable. More. Lay your course by that and you'll be on it before you've cleared the point."

He turns. A face like a walnut, and the eyes of a man who's heard it all.

"Thirty years," he says, "I've taken ships out of this harbour."

"Then for thirty years you've had the tide with you."

The deck goes so quiet I can hear the goat chewing.

This is where I'm put ashore. First hour aboard, I've called the master a fool in front of his crew, and all I have to show for it is the colour of some water.

"Show me," says the voice from the wall.

He's behind me. I turn round.

He's younger than the stories: tall, very still, burnt brown, with black hair cropped short and eyes the pale grey-green of shoal water over sand. No coat, no wig, a white shirt open at the throat.

He's barefoot. The most feared captain in the Caribbean is standing on his own quarterdeck in bare feet, waiting for me to show him his mistake.

I pull the pencil out of my hair, and half of it comes down. I lean over the binnacle and draw the spit where it lies, a hatched tongue of sand, soundings beside it.

"Three fathom," I say. "Two and a half at low water. You draw what, twelve feet?"

"Thirteen, laden."

"Then you'd have touched. Not wrecked. Touched. Sat on it like a hen till the tide came back, with every ship in the harbour watching."

He looks at my figures for longer than figures need.

"Master," he says, not loudly, "we'll go out on Miss Kerr's line. Leadsman in the chains."

"And if she's wrong, sir?"

"Then you may tell her so in front of everyone. She's earned that much."

The master shuts his mouth. Then, God help him, he nods to me.

He holds out his hand for the pencil. When I give it, his fingers close over the end of it and the ends of mine, and stay a moment longer than a pencil needs.

A gig pulls out from the Navy yard, a clerk in the stern clutching a paper.

"Mr Ashby's compliments," the clerk calls up, "and the Admiralty requests sight of the navigator's commission, and of any surveys in her possession."

Ashby is the Admiralty's surveyor here. Once, he declined my best chart, by letter, because he did not buy from engravers' daughters.

The captain doesn't even go to the rail.

"Tell Mr Ashby I remember what his sloop was carrying when I pulled her off the Serrana in July," he says. "And that the Admiral doesn't. Yet."

The clerk's face does something complicated. The gig goes back the way it came, rather faster.

"What was she carrying?" I ask.

"Something he'd like me to forget."

"Will you?"

"That depends how badly he wants your surveys." He gives me back my pencil. "He's spent three years looking for a way through that bank, and run aground twice."

"And you want me to find it for you."

"Chart me the passage, Miss Kerr." He says it like a man setting down something he's carried a long way. "I'll chart everything else."

"Everything else being?"

"Weather. Spain. Mr Ashby. Whatever comes at you while you work."

"That's a great deal of everything for one man."

"I've had years to practise."

"Do you own shoes, Captain?"

"Several pairs."

"Have you met them?"

"They're for land." The corner of his mouth goes, and comes back. "I don't go ashore."

His cabin runs the width of the stern, all windows, the light off the water moving on the ceiling.

Every inch of wall that isn't glass is chart, and every chart is mine.

Years of my coasts. The one Ashby wouldn't buy. The one I got wrong, with the corrected printing pinned neatly over it. It's either the most flattering thing a man has ever done for me, or evidence.

In the middle hangs the Firth, the worst water in Scotland and the first thing I drew that went to the engraver. It went out under my father's name, like everything did.

This copy is salt-stained and worn soft, its folds backed with sailcloth where they wore through. There's a thumbprint of tar on the tide table.

"Collectors buy my father's with mine," I say. My voice isn't quite my own. "That's not strange."

"No."

"How many times have you sailed by this?"

"Four." He stands beside me, not touching, and puts his hand flat on the chart to hold the curl down. "The first time in a gale, at night, the tide running nine knots. It's the only chart with the set right."

"I know it is."

"I know you do. I'm alive."

I look at his hand on my coastline. Brown, rope-hard, holding my work flat.

Nobody has ever used my work hard enough to wear it out.

I put two fingers on the back of his hand.

He holds still. Not calm. Still, the way you hold a lead line when you've felt the bottom and daren't lose it. A muscle goes in his jaw. His hand stays flat under mine, and from the way it doesn't turn over, I know how much it wants to.

He's wanted this for a long time. I don't know how I know. I just do.

"Miss Kerr," he says, very low.

"Captain."

"You'll want to see the Serrana. What there is of it." He doesn't move his hand. "It's on the desk."

I take my fingers back. It's harder than it should be.

"You could have had a London man with an Admiralty warrant," I say. "For a third of the price."

"I could have had a London man who puts that spit where the Admiralty put it."

"So you're paying for accuracy."

"I'm paying," he says, "to have you in the room where the mistake is."

The Admiralty sheet on his desk shows the Serrana as a ragged blank, miles of nothing labelled FOUL GROUND, as if somebody gave up.

I know that blank. For six years a man I never met wrote me letters from these waters, and in one of them he said there was a way through the Serrana that no chart showed. Last winter, the letters stopped.

Beside the sheet, holding its corner down, is a seal.

Brass. A compass rose. The north point chipped off.

I have traced that chip with my fingertip in the red wax of twenty-eight letters. I'd know it in the dark.

I don't look at it. I don't say a word. I file it, the way you file a sounding that doesn't fit, and I keep my face exactly where it is.

There are two ways a man comes to own another man's seal. One of them is a love letter.

The other is a grave.

We sail at dusk, on the land breeze.

I stand by the wheel as the Reprisal slides down the harbour in the dark, and the leadsman sings out from the chains. By the mark five. And a half four. Then, abreast of the third cay, by the deep six.

Deep water. A cable east of the spit, exactly where I said.

The master touches his hat to me. "Miss Kerr."

"Master."

"Like a hen," he says to nobody, and goes forward shaking his head.

The captain's boat is still alongside, the boy at the oars. Any minute now it goes back to the quay, with or without me. Behind us, the lamps of Port Royal are coming on along the water.

The captain comes and stands at my shoulder. Not touching.

"Ashore, Miss Kerr?" he asks.

He means it. If I say yes, the boat takes me back, and no man aboard will ask why.

I think about a chipped seal, and a passage nobody has charted, and a voice through a wall that said I didn't guess.

"Further out," I say.

He nods once, as though I've given him a bearing, and turns away to his ship.

I've had the key in my hand all evening. I catch his sleeve, put it in his palm, close his fingers over it, and go below without it.