It was winter when she returned, hauling herself up the rocks from the sea, slippery with new skin, dimpled with fat. I opened the door and saw her there. The full moon shone in her teeth, and her face was blunt with cold. She came inside and sat down at the fire without saying a word. When she put her hands up to the heat, I saw they were plump and broad, ribbed like palm fronds. She held them so close I could see the shadow of the flames through them, and I wondered at how she did not burn.

She would not take anything to eat or drink. I offered her my room, but she refused and instead slept in the armchair, slumped like an old coat.

When I woke, I knew she had gone. I opened my bedroom window, the frame stiff with salt, and looked down at the sea. I wanted to go after her, but I knew that if I walked into the waves there would be nothing for me there. Only the pull of the undercurrent, ruthless and silent and cold.

This house is not mine. It belonged to my Nan. Although she left it to me, I still cannot think of it as my own. The sea has the stronger claim.

It is more than a century old, and its foundations are turning to salt and foam. Soon there will be waves lapping at the back door and barnacles adorning the ceilings and floors. The garden I used to play in with my sisters during the school holidays has eroded into sand, the callistemon and morning glory all gone. So too the big eucalyptus and the rope swing, peeled from the garden by a summer storm and pitched into the waves.

Now, the tide leaves great nets of seaweed draped across the lawn where we once played. I collect the weed each day and sell it to a company that turns it into all sorts of things: nori sheets, organic face masks, fertilizer, women’s multivitamins. Even fuel.

There are no other jobs nearby, and hardly anyone left around. They’ve all moved to higher ground. To the north is a small bay that used to be a popular tourist destination before the seas began to rise and flooded all the beach houses. To the south, the tidal pools I was always afraid of as a child, the water sucking at the black rock with dreadful power.

Nan was the only one who ever went exploring there, wearing her wellingtons and a gaudy headscarf. She would bring back wonderful things: shells, bits of glass tinted green and red and blue, volcanic rock, fish bones, and, one time, a small purple starfish with bristled limbs, each one like a lumpy toothbrush.

We kept that starfish overnight in a bowl in the sunroom at the front of the house. Nan made some sketches of it after dinner and my sister and I sat at her feet, pretending to do the same, but drawing mermaids and unicorns and dragons instead. Nan was a good artist. Her favorite subjects were her garden, her family, and her rock pools. She exhibited her drawings in a few local shows. Her photo appeared in the newspaper once after she won a prize from the local art society with a portrait of me holding a branch of myrtle. I took the clipping to school for show-and-tell.

After we went to bed that night I couldn’t sleep, so I snuck into the sunroom to take another look at the starfish. It hadn’t moved. In the moonlight it looked bony and ancient, a bit like Nan’s hands. I fell asleep at the desk. Something must have drawn Nan from her bed and into the spare room to check on me and my sister. These days I don’t like to think about how scared she must have been when she slipped through the door and turned the light on only to find me missing, my covers cold and corrugated, my slippers and robe still there. I see her coming down the stairs, turning all the lights on. Going from room to room. There I was, slumped over her drawings, the graphite from the page smeared on my cheek like war paint. She carried me back up to bed and tucked me in again. The next morning, I barely remembered it. I just know that when I came down for breakfast Nan had already returned the starfish to the pools and it all felt like some weak, senseless dream. Nan didn’t yell at me over our Weet-bix and cartoons like other adults would have done. Instead, her smile was like a saint’s. I thought you’d wandered off into the ocean, she said. I almost called the police.

A week of rain, then I see fresh signs of her: a shallow trench in the sand where something heavy has dragged itself ashore. I go looking for her, walking as far as the rock pools, but it is slick and dangerous there, and the rains have fogged the surface of the water. This place now seems to be full of cold desires that repel me. I stumble away, back to the house.

The wind is loud that night, carried on some freezing current from deep within the sea. A shadow moves along the shoreline. I watch her from my bedroom window: a tract of black against grey, washed flat by the moon. As the skies open, she seems to become bolder, twirling, darting, slithering, dodging: her body parrying each thrust of the waves. There is a crack of lightning, and I see her clearly for a moment—sleek, powerful, dripping—and then she leaps down to the shore and darts through the breakers as though she was born to it, as though she was crafted by the forces of the sea.

When I moved in with Nan, it had been three months since my daughter disappeared.

Nan said she wasn’t managing very well on her own. That her memory was going. But the truth is that I was the one barely coping, and Nan had always been the person I was closest to in my family, her house the one I thought of as home.

This is all we knew: Amy had gone out to dinner the night she finished her law exams and never come home. Her friends had last seen her getting into a taxi outside the Mexican restaurant they’d stayed at until closing time. There was a photo of Amy from that night wearing a too-big sombrero and holding a turquoise cocktail. For some reason, that’s the photo they chose to use in all the news reports.

For the first few weeks, I sat by the phone waiting for the police to call. But when they did, they never had any real news. They were still following leads, the detective said. But they hadn’t found the car. No witnesses had come forward. There was grainy CCTV footage of someone who could be my daughter buying cigarettes at a service station. But she didn’t smoke, I said. Nevertheless. They were investigating.

I tried to go back to work, but my colleagues’ kind words and gestures just made me feel pathetic. Their convenient casseroles. Their thoughts and prayers. Their offers to cover the late shift or give me rides home. The only gesture that I felt made any real difference came from the intern, who offered to perform all my patients’ enemas for me. That was a real blessing. Meanwhile, the patients themselves were just as bad in their own way. They required so much attention. Dispensing their medication, changing their dressings, turning their bodies, comforting their families—it was all too much like love. I couldn’t do it. How could I, when she still hadn’t been found? Every brow I wiped. Every hand I held. Every vial of blood I drew, bedpan I cleaned: everything reminded me of her body, and what might have happened to it, and where it might be now.

I rise with the sun, swallow down a bowl of oatmeal porridge and a cup of English Breakfast, and then go down to the shore to bring in the weed. I wear Nan’s wellies, one of her headscarves—the one with the Japanese cranes—and a pair of thick gloves made for handling wire. The weed can be dangerous; I’ve found broken glass, razor blades, syringes. I think these gloves must have belonged to Pop. They’re too big for me, so I secure them at the wrist with rubber bands.

After I’ve brought in the weed, I comb through the strands and remove the detritus caught there: plastics, fishing line, bits of dead coral.

Even with the gloves, my hands have become sensitive to anything that doesn’t belong. They stutter over an alien surface: hard, curved, tapering. I pull the object free, take it outside and rinse it under the tap.

It’s the color of tortoiseshell. Heavier than it looks. Pulling off my gloves, I trace its spiral structure. I know what it is, but I Google it anyway, just to be sure. I scroll through the image results. They could almost be mistaken for pine cones or exotic flowers. But there is no question.

It’s an egg. The egg of a Port Jackson Shark.

Ten years ago, I’d taken Amy to the Sydney Aquarium and we’d spent a great deal of time at the touch pool. She was not afraid, as I had been as a child, to reach in and stroke the starfish, the anemones, the cucumbers. There had been shark eggs there, too, and she’d lifted one, almost identical to this, out of the shallows and held it up to the light.

“What is it?” she asked.

We’d had to check with the attendant. When he told us it was a shark egg, Amy was horrified. She hurried to put it back in its place in the pool, then stepped away, her damp hands scrunched in her pockets.

“What’s wrong?” I asked.

“It’s not right,” she said. “We shouldn’t be allowed to touch it.”

The attendant tried to reassure her.

“The egg is empty,” he said. “The baby shark has already been born. It’s just for display.”

But Amy shook her head, her lips pressed together so hard her cheeks dimpled.

“No,” she said. “I felt something in there. It was alive.”

The attendant looked at me. I shrugged, a vague smile on my face, and he turned away to supervise a school group that had just come in with their harried teacher.

In the gift shop, we found plastic replicas of the shark eggs on keychains. Amy didn’t want to buy anything, not even the stuffed toys, so I got us ice creams instead. We came out into the sun and sat on the pier licking our Golden Gaytimes and looking down at the green water, thinking of the worlds we’d just seen beneath.

In Nan’s sunroom, I place the egg in a glass jar that is only just large enough, and position it on the windowsill where I’d once fallen asleep watching the starfish. Its companions: a mix of objects Nan found in the rock pools and others brought to me by the sea. Unusual shells, stones shaped like hearts, the skeletons of large bony fish, and even an ammonite fossil.

Next to the egg is a monocle, the chain still attached. I put it on and close one eye, peering through the cloudy lens. The room brims with hazy, colored light, and I wonder if this is what it is like for the creatures living in the pools. The surface of the water so smooth I would slip through and disappear without a trace.

I ended up taking leave from my job and began walking for hours to fill my days. At first just around my suburb, but then into the city, all the way down to the harbor and back. I left the house at 8 a.m. and returned after it was dark. I patrolled public spaces, searching everywhere I could think of. Everywhere we’d ever been together. The mall. The library. The aquarium. Especially playgrounds. There had been another case, maybe six months ago, of a young woman’s body found in a suitcase in a playground. I don’t know what I hoped to find there, but I looked anyway.

I stopped answering the phone. Stopped watching the news. Amy’s story had slipped from the headlines by then. I dropped by the police station twice a week to check in on the case, but my conversations with the detective became shorter and shorter. Sometimes I would just sit in the lobby and watch people coming and going, hoping to catch Amy’s face in the crowd.

When she couldn’t reach me by phone anymore, Nan sent a letter. I found the envelope nestled between a brochure for cheap furniture and another for eyebrow shaping. I knew the writing.

Dear Emma, it read. Would you like to come and stay with me for a while? You can have your old room. I haven’t changed a thing.

It occurred to me then that perhaps Amy had gone south. Perhaps she had returned to the place where she’d spent so much of her childhood. It felt—not right, but it felt like something.

The next day, I took the train down the coast to Nan’s. I left my house unlocked, the front gate open. A note on the fridge letting Amy know where I’d gone, in case she came back while I was out.

The days are getting shorter, colder. The Bureau of Meteorology issues a severe storm warning for a Sunday night. A cold front is pushing up the coast, bringing strong winds and torrential rains. Big ocean swells are predicted. I prepare as best I can, getting some sandbags from Bunnings to reinforce the backyard that is slipping underwater day by day.

The storm hits at 10 p.m. I am already in bed, lying under two quilts, my fingers and toes as cold and hard as pieces of sea ice. The storm rages for hours, and I drift in and out of sleep. I don’t hear the tides rush up and wash the sandbags away. I don’t hear the front windows break downstairs. The wind is too loud. I only discover these things in the morning when I come down in my pajamas to survey the damage.

The sunroom’s stained glass is all smashed, my precious artefacts strewn around the room as though deposited by a sullen tide. I begin to sweep up, picking out my favorite objects: a fist-sized stone shaped like a heart, the jawbone of a sea bass, and, of course, the shark egg.

That afternoon, I go down to the shore. It is quiet after the storm, although there is a grey sheen to the water, like it’s still wearing a foul mood. I place the objects in the shallows one by one and watch as they are swept out and disappear.

Last is the egg. It dips in and out of the waves for a long time, until finally it gets caught in a rip and is borne away.

Two nights after the storm, she comes to me for the first time.

She is different, but I know it is her. Her teeth are pointed. Her gills suck at the blustering skies. She is grey-black and plump, and her eyes are like pieces of black glass in the flat of her face. I watch her heave herself up the shoreline. She is heavy and yet elastic, her body snaking forward, the slits of her nose pointed at me, smelling me out.

I open the back door and she slips inside. I have some salmon in the fridge and I give it to her raw. Then we go into the lounge room and I light the fire because I am cold. She is not afraid of it. She holds her hands up to the light.

In the morning, we walk down to the sea together. I want to touch her, to see what her skin is like, to see if she is warm or cold, soft or hard. But she moves away before I can, shooting beneath the waves, the plume of her turning to salt and foam, and it is like she was never here.

I tape over the window with plastic sheeting and continue to sell seaweed to pay the bills. I comb the weed for more shark eggs, but find nothing.

She comes again, a week later, and then two weeks after that. But with each visit, she seems more remote. She does not stay as long. She turns her nose up at my food.

A month goes by. There is a change of moons, and still, she does not come.

The last time I spoke to Amy was over the phone. She was in the middle of studying for her contract law exam. She had to sit the paper at 9 a.m. the next morning. She felt like she didn’t know anything even though she’d been studying for weeks. I reassured her that everyone probably felt the same way.

We planned to take a trip down to Nan’s place in her summer break, unless she got a clerkship at one of the firms she applied to. Nan’s paintings were going to be in an exhibition at the local library and we wanted to take her out for dinner after the opening to celebrate. Nan had sent Amy and me pictures of her works-in-progress with her old camera phone, but the low resolution made them look distorted, abstract—like black holes in space, nebulae; the kind of stuff she’d never painted before. Later, I wondered if it was a symptom of her mind going astray, her hands wandering into confused places, following her degenerating neurons. But by then, Amy had been missing for months and Nan was being assessed by an aged care physician for her mental capacity. It felt like I was losing everything. Even the house would be gone soon. Everything slipping under, ebbing away, leaving me safe on land, while all I wanted to do was swim out and out, to find what used to be mine.

The hospital calls. They ask if I’m available for some casual work. They always have shifts to fill in Emergency. They know I am capable and efficient.

In Emergency, you don’t become attached to your patients. You assess them quickly. You send them on to have their bones set, their brains scanned, their appendixes removed.

This, I think, is a start. This is something I can do.

The last time, she does not come ashore. From the kitchen, I see her in the shallows, slipping in and out. I feel her weight in the darkness. There are no stars. The water seems to have its own light. It slides off her back, her face, her fins. I hesitate in the doorway. Something stops me from going to her. I realize: she does not belong here. And then she turns, and dives, and the water parts around her like she is nothing. Like she is water. She pours away, into the black, and I feel the tide receding, leaving me a hundred light-years away on land, my hand on the knob of the back door, my feet warm in their bed socks, the fire at my back.

I close the door. I know she is never coming back. A creature like that survives best on her own. And she’s not the one I wanted when I sent the egg away. She’s not the one I lost. She is her own living thing. I love her, yes. But now I have to give her up to the sea.