We’re delighted to bring you  Heavy Water, a superb short story by Katherine May, the author of our new release Burning Out.

Heavy Water

The water was getting cold; blood-temperature, in fact, as Natalie had the strange sensation of not being able to feel it. She had read - somewhere, she couldn’t remember - that your heart would stop if you stayed in blood-temperature water for too long.

Better safe than sorry. She leant forward, inched on the hot tap, and sat there for a moment, savouring the seep of warmth as the boiler kicked into action. The Radox had disappeared, leaving perfectly clear water in the bath, slightly blue, through which she could see the pale form of her own body.
She returned her attention to what she liked doing most. She let her fingertips do a recce of the stiff hairs on her legs, and began to pluck at them.
The thickest hairs, as she expected, surged out to reveal balled roots that made the faintest pop as they emerged. Those that were crowded three to a follicle were the most painful, but slid out slyly if she managed to grip all of them at once. The ingrown ones needed to be snouted out with the tip of a needle. Sometimes, she would find one that had been buried so deeply and for so long that it would loop out to unfurl into an impossibly long hair, weak and anaemic from never having seen the light of day.
Natalie carried out this labour most mornings, first on the left shin, and then the right, her head bent over, her bottom lip drooping in concentration. By the time she looked up her neck was stiff and sore, and her legs were blotched with angry little marks where the hairs had been. She reached over onto the windowsill and checked her watch: 10.30. Out of the danger zone. Surely it was too late for anything to happen today.
But then it started, as it always did when she let it peer around the edges of her consciousness. Along with the sun that was streaming through the open window came the sound that she had been half-expecting all along.
It began with a splash, a flat belly-flop that made Nat’s heart clench. There was a short pause, and then they came, the slow waves, the sound of a heavy breast stroke. She dropped her tweezers and they floated to the bottom of the bath. The stroke became slower, weaker, gradually harder to define, until there was a final, small gulp that you could only hear if you were listening for it, and then nothing.
“Morning, Cara,” she said, as she fished around for the tweezers and turned the tap for more hot water.

*

It was 1985 when Teresa and Owen bought the house. It was a new-build, part of an estate that was being developed on the site of an old chalk quarry. When the estate agent showed them around, the house was nothing more than an arrangement of breeze blocks and cement. Teresa walked over to the window that didn’t have glass in it yet, and peered down the short yard and over a steep chalk cliff.
“It’s a bit high-up,” she said, biting her bottom lip and gripping the window sill as if she might be sucked into the chasm with the least vibration from the pneumatic drills that were preparing the land next door.
“Don’t worry about that, it’s going to be flooded next week.” The estate agent swept his clipboard out expansively across the view. “By the time you move in it will be a beautiful lake.” He winked at Owen, who rolled his eyes at his nervous wife. The first house on the Speldhurst estate was sold.
The twins weren’t even born yet. They were just a notion, at this stage.
But by the time Teresa and Owen moved in, though, they were more than a notion.
Teresa didn’t know it yet, but two embryos, furled like fiddleheads, lay symmetrical in her womb. Still only the size of neat broad beans, they were already big enough to make Teresa’s first action in her new home a sprint to the kitchen sink to bring up that morning’s breakfast.
As she rinsed her mouth under a tap still clouded with tile grout, Teresa’s eye was caught by something blue beyond the window. She straightened and turned to catch her first view of the lake.
It wasn’t as she had expected, not at all. Unlike the illustrations in the brochures, Speldhurst lake was not a rough-edged puddle ringed with bulrushes and droned by dragonflies. It was blue, the intense blue of a swimming pool, the blue of the Caribbean sea in Bounty adverts. It glowed off the white slopes that surrounded it with such intensity that Teresa almost screamed.
Owen’s voice drifted through from the living room. “Will you look at that lake?” There was wonder in his voice, the same way it had sounded when they arrived at their honeymoon cottage and he’d realised that you could see the sea from the bedroom window. “It’s the most beautiful blue I’ve ever seen.”
But Teresa was suspicious.
Suspicious that water so blue could exist under such a muddy sky.
Suspicious that something so beguiling could be anything but dangerous.
Suspicious that she had eaten something that hadn’t agreed with her.
She was wrong on only one count. The blue of the lake was real alright, tinted as it was by the presence of millions of tiny chalk particles that hung suspended, lending it its eerie blue.
Yet they were little traitors, these particles; they were minute sirens that lured their prey into the lake with the promise of paradise, the most intense blue waters that you’d ever seen. But as many swimmers found out, they were also lethal. For the quarry was so deep that the sun never heated it, and so the first blow for the unwary swimmer was the intense cold that set the muscles like stone.
The second blow was much more insidious. As the swimmer moved around in the water, thrashing their limbs in a vain attempt to warm up in the frigid pool, the little white particles did their work, accumulating on the swimmer’s cool body, building up a powdery film that slowed their joints and made them heavy, heavy enough to have to fight against the water, heavy enough to feel the soft pull of the deep.
Heavy enough to drag them under, as swiftly and efficiently as quicksand.

*

Around eleven, Teresa made a nervous tap on the bathroom door.
“I’ve made some tea, love. Will you come out and drink it?”
Natalie rinsed the pumice stone that she’d been using to buff the soles of her feet, and eased her way out of the bath. She hopped on tiptoes to the door, conscious that she was dripping water all over the floor, and snapped back the lock, opening the door a crack so she could push her hand through.
“Give it to me, then!”
Teresa placed the mug in her hand, which was swiftly withdrawn. The door locked again.
“I was hoping you might come out and drink it with me. We could have something to eat as well.” Even as she said this, Teresa could hear Natalie easing herself back into the bath again.
“Later,” she said. “I’m not done yet.”

*

The lake haunted Teresa as she rushed to decorate the house in time for the arrival of the twins. It glared at her like a big, blue, unblinking eye. It was as bright and as sickly in sunlight as it was on the dull, clouded days that seemed to dog the new estate. Its demanding pull, the ungenerous way that it claimed her attention no matter which room she was in, made Teresa cast it in her mind as a monstrous baby, ravenous for her attention. Even all the houses on the estate seemed to point to it, as if they had twisted towards it like flowers towards the sun.
Owen was feeling the pull of the lake, too, but in a joyous way, the way that children are drawn to the sea. He watched the lake from the wide living room window at all hours of the day, observing the airy translucence of the waters in the first morning light, the moody blackness that rolled under its surface when it rained, the redness that flecked its ripples at dusk. He traced the fence that ran around its perimeter with his eyes, looking for a way in, wondering why on earth someone would create something so beautiful only to block it off.
One grey Sunday, a month after they’d moved in, he decided to lead an expedition to reach the waters.
“I’m not sure if it’s such a good idea,” Teresa said, rubbing the bump that was emerging on her abdomen. “I don’t want to take any risks at this stage.”
“Come on Terry,” said Owen, putting his arm around her shoulder while looking out of the window, “it won’t be long before you’re too big to get down there.”
“But you don’t know what’s lurking in that water.”
“Sea monsters?”
“Germs.”
“I wasn’t planning on swimming. I’m bringing the boat.” He pointed at the sofa, where a miniature yacht was sitting, painted blood red with a high white sail. It was a relic of his childhood, bought grudgingly by his father from a stall at a craft fair, when a young Owen was making too much fuss. He’d never had the chance to sail it; instead it sat propped on his bedroom windowsill until he’d moved into a house of his own, when it had taken residence in the bathroom.
It was due to this little flourish that Teresa found herself slipping down the smooth chalk towards the chicken-wire fence that marked the perimeter of the lake. Once they reached the fence, Owen rattled for a few seconds, and then started to trail around it, feet bent against the steep slope that it intersected, Teresa following with a hand clutched across her fragile belly.
They had slipped and stumbled three-quarters of the way around the lake before Owen concluded that there wouldn’t be a gap in the fence, and that they would have to make one for themselves. Teresa sat on her jumper and watched as he tugged the raw edge at the bottom of the wire mesh, and then, when it began to curl upwards, yanked it hard so that it frayed away from the concrete post that supported it and created a gap big enough to get through if you crouched. Conscious that things had already gone too far, Teresa crawled through.
Up close, the lake was less startling. It was too quiet, too still; it hunched between ragged white cliffs from which nothing grew. The overall effect was of starkness rather than natural beauty. The waters were duller up close, and cloudy; they reminded Teresa of spilled paint.
Owen felt deflated, too. From above he had savoured the calm beauty of the blue lake, the unsettling perfection of the scene. Down here, though, it was chilly and dark, and seemed far from civilisation. He had imagined a serene picnic spot with lapping waters and sparkling light; instead he felt as if he had been stranded in a bizarre lunar landscape. Above them, the houses of the estate crowded around them with blank eyes.
The water snapped at his heels. He removed his shoes and socks, rolled up his trouser legs and sat down to dip his feet into the lake. Then, he carefully set the yacht down on the surface. It bobbed a little, and then trembled so he held it by its sail, and pushed it out from the shore. For a few moments it looked steady, purposeful, but then the boat faltered, and began to list left and right, in increasingly daring swings like a pendulum. Finally, as it took one final, exaggerated loop towards the surface, the sail caught in the water. It was as if the boat was consumed. It didn’t capsize so much as be sucked into the lake at such a pace that Owen and Teresa could only stare.
After it had vanished completely, Owen began to wade towards it, but Teresa held onto his sleeve. “Don’t,” she said. He knew what she meant. He walked back onto the bank and sat down to put on his shoes and socks.
“Jesus,” said Teresa, as her eyes fell on his feet. They didn’t look at all like feet that had just been pulled out of a lake: wet, pink, glistening. They were covered in a thick film of chalk dust.

In time, the houses around the lake filled up, and the estate began to feel a little less foreboding. Despite this, Teresa took the first opportunity she could to hang nets and heavy curtains over the windows that faced the lake, in an effort to dull its piercing blue.
Owen didn’t put up much of a protest; he was no longer so keen on his view of the lake either. The spell that it cast over all the new Speldhurst inhabitants had been abruptly broken one afternoon in June, when a little boy named Simon Grant strayed from his own back garden, scrambled down the sheer chalk banks and found his way into the lake via a gap in the fence. Five people watched him drown through their picture windows that so often drew them to gaze over the waters, but not one of them could do a thing to help him.
The weekend after, Owen climbed down the lake by himself, so that he could repair the hole that he’d made. It did no good. A month later, two teenagers, a girl and a boy, drowned whilst skinny-dipping drunk at three in the morning. Nobody saw them.
Before long, the lake and its heavy water had taken on a mythical status for the estate, looming in their imaginations like a curse.

*

At midday, Natalie’s stomach began to rumble, and a wave of watery sickness passed through her. Her fingers, now so wrinkled that they were numb, looked as though they had been gathered by fine threads under the surface of her skin. She gazed at her feet, and wondered if she shouldn’t nevertheless paint her toe-nails, but then her stomach lurched in another wave of nausea.
She eased herself out of the bath, and just for a moment caught a glimpse of the lake through the open window. The sky had grown overcast, turning the lake a milky turquoise. She was safe for now; Cara only came in the sunshine. Nat turned her back on it and dried herself off.
Downstairs, everything was quiet. There was a note on the kitchen surface from Teresa to say that she had gone to work, and that there was cold pizza in the fridge. After a little searching, Nat found it under a layer of foil, and ate it in front of the television, leaving the burnt crusts. Then, she sat and enjoyed the grey sky on the patio, until the first fat drops of rain began to bombard the hot concrete.

*

Cara and Natalie were born in November. They were different right from the start.
They didn’t even look alike; Cara was pink with a fuzz of dark hair, and seemed all fists and knees as she came out. Natalie emerged ten minutes later, almost blue, and tiny and hunched. When she finally cried, it was a thin, high mew, like a lost cat’s, that was barely audible amid the racket her sister was making.
“Is she okay?” Teresa asked as they handed Cara to her and wheeled Natalie out of the room in a perspex cradle. “Where are you taking her?”
“She needs an incubator, love,” said the midwife, as she primped the blanket around Cara’s face. “She’s very underweight.”
“Why?” Teresa turned to Owen, who seemed to have flattened himself against the wall by the bedstead, his face a grainy white. “Why’s she so small?” Owen opened his mouth as if he was about to speak, but then closed it again, and ran his hand over his head, revealing a deep patch of sweat under his arms.
“If often happens with twins,” said the midwife. “There’s usually a stronger one, who gets more of the space and the food. One’s often much bigger than the other. I read somewhere,” she looked at Owen decisively, as if he would particularly appreciate this information, “that it’s common for one twin to just absorb the other one, in the early stages of pregnancy. You’re lucky to have two.”
Teresa thought about the tiny baby she’d glimpsed being wheeled out to the care unit and looked at Cara’s ruddy face, and didn’t feel so lucky. She carefully handed her eldest daughter over to the midwife, and told her she needed to rest.

Natalie improved slowly, gaining weight so that she was five pounds before she left the care unit.
While she was pregnant, other mothers of twins told Teresa that she should prepare herself for a double burden, that she would feel constantly pitted against the impossible task of keeping both of them clean and dry and quiet at once. When she found that this was not the case, Teresa was far from pleased.
Cara did all the things she expected (kept her up all night, bad-temperedly demanded her attention whenever she tried to get on with the housework) and more; she somehow seemed especially voracious, grabbing and sucking at Teresa’s breast at hourly intervals, and screeching with the force of a compact hurricane.
Perhaps Teresa’s double burden came from Cara alone, then, because Natalie was barely there. She would lay silent in her cot, her eyes unfocused, and would hang limp in Teresa’s arms when she would lift her out and try to coax her into life. At feeding time, she would gum half-heartedly on Teresa’s nipple, before drooling out the meagre amount that she had managed to suckle. Teresa wondered if she was the only mother in the world who wanted her baby to cry more.
The health visitor was superficially helpful, but Teresa always detected a hint of accusation in the advice she offered. Natalie was a perfectly healthy baby, which meant that either Teresa’s breast milk was too thin, or that she was feeding at the wrong time of day. Teresa doubted that either of these could be the case, given that Cara had grown peculiarly robust on the same regime as Natalie, but she nevertheless followed the advice; Natalie was fed a range of formula milks, in bottles with a range of teats, following a strict timetable drawn up by the midwife; but still Natalie remained a skinny baby, with sallow, baggy little face.
When they were both two months old Teresa finally worked it out. Cara caught a bug of some sort that raised her temperature so that she felt like a lightbulb under Owen’s hand when got her up that morning. It turned out to be nothing serious, but the two days that Cara spent grizzling quietly and refusing her milk had an interesting effect on Natalie. She bloomed. She began to wail at three-hourly intervals, and then to gobble greedily at the bottles of milk that were offered to her.
As Cara got better, though, Natalie’s appetite declined, and she reverted to being a shadow again. For the first time, Teresa realised that there was something unusual about her twins. She wondered whether, if she fed Cara a little less, that Natalie might have a chance to grow a little more.
She didn’t dare tell Owen, but secretly she began to leave Cara crying for longer before each feed. It seemed that it was only when her sister was really hungry that Natalie would revive a little and begin to demand food herself. Teresa soon got into a routine of feeding Natalie with Cara screaming in the background.

*

Owen came home at seven, as he always did.
He kissed Natalie’s head, and sat down next to her on the sofa, snaking his arm around her shoulders.
“What did you get up to today?” he asked.
“Not much.”
“She was locked in that bloody bathroom for four hours again,” shouted Teresa from the kitchen.
Owen withdrew his arm. He opened his mouth to speak, and then closed it again, shook his head and exhaled heavily, slamming his hands onto his knees. He got up and walked into the kitchen, and then came back again, fast, saying, “You think you’re the only one, don’t you? The only one that’s affected by this?” Natalie dropped her head, but Owen bent down so that his face was level with hers and began to shout, “It’s bad enough losing one of you, but when the other one locks herself away all day…” He tailed off, and rubbed his fingers flat against his rigid mouth. “Get a job, Natalie. Or go back to school. I won’t have you sitting in this house all day pining for Cara. It’s time you got on with it. Everyone else is.”
Natalie got up and ran upstairs to her room. She locked the door with the brass bolt that Owen had fitted for her when she was thirteen; then, it had guarded her new need for separation from her sister’s identical body; now, increasingly, it was serving as a full stop at the end of most of her conversations with her parents, a metallic click that signalled that she had nothing more to say.
She switched on her television, and turned the volume up loud so that she couldn’t hear Owen and Teresa arguing downstairs. How would they react if they knew there was a ghost? If they couldn’t handle her time in the bathroom, what would they think if they found out that she was listening to Cara swim by?
Only on sunny mornings.
Natalie thought it best that they didn’t find out. She watched a couple of soaps and the end of a film before falling asleep.

*

By the time the twins were six, one thing had been established in the mind of every child on the estate: they were not to go near the lake. Teresa and Owen were so careful to warn the twins of its dangers that they both imagined it would suck them in, like a hungry blue monster, if they ventured near.
Certain things had been established about the twins as well. Firstly, they did not like to have the same haircuts or to wear the same clothes. Secondly, they would get along very well together as long as they were not expected to share anything. And thirdly, they had a link.
The idea that two beings who were cleaved from the same zygote should somehow share a consciousness is not an unusual one; Teresa found that it was the first thing most people asked.
She had noticed, though, that our twins had a rather unusual link. It was inverse. Whatever one was feeling, the other would feel the opposite. When Cara was hyperactive, Natalie was exhausted; when Natalie was upset, Cara would become inappropriately happy. Or, as was most often the case, when Cara was well, Natalie was ill. It was as simple as that.
Take, for example, Cara’s first ballet class. Aged five, she bounded home in her pink leotard, and skipped around the living room, before sitting down to show Natalie what she had learned: good toes, bad toes, good toes, bad toes. Natalie had been lying listless on the sofa all afternoon, but she sat up to watch the show that her sister was putting on.
“Next time we’re going to learn how to spin,” Cara called out as she attempted a few heavy leaps that sent the display cabinet rattling. “And Mummy’s going to buy me a bag with a ballerina on it.” She drew up close to Natalie, and held both of her hands. “I’ll show you how we skip, if you like.”
Natalie smiled, enjoying her part in her sister’s whirlwind; and as she did, her bottom lip cracked, and a vein of blood trickled down her chin.
Teresa didn’t let Cara go to ballet again. She soon learned that the only way to keep both of her daughters safe and well was to restrain Cara’s exuberance, to keep her from the things that she liked too much. Too much of a good thing was always bad, everyone knew that, although Teresa didn’t think it was very good idea to tell Owen what she was doing.
She didn’t tell the twins, either. She carefully rationed parties and days out, and monitored coughs, colds and chills. She saw herself as a mediator between the highs and lows of the girls’ lives, guiding them towards a path that maintained an average, a balance. For every cut knee, or playground upset there was a consequence, but then what, in life, does not have consequences? Teresa sometimes had to remind herself that the daily juggling of her daughters’ lives was not normal.
The twins grew. At eleven, they chose different secondary schools, and so began to find themselves in company that didn’t even know that they had a doppelganger lurking at home. They soon had different sets of friends, different tastes in music, different lives. Teresa wondered if they even really noticed each other any more.
By the age of fifteen, it was hard to call them identical. Though they were the same height, the same weight, and had the same fair skin, Cara wore her red hair straight and long, whilst Natalie had a friend hack hers into a scraggy bob, and dyed it black, then pink, then blue. The same eyes, nose and mouth were buried under two entirely different concepts of make-up; the same bodies wore opposing clothes. Tidy Cara began to complain that she was embarrassed to be seen with Natalie, who had forced a thumb-hole through every sweater, and had biro-ed slogans on her school bag.
They lived fairly sedate lives, enforced by Teresa. Under the banner of discipline, she had banned boyfriends, sleepovers and weeknight activities.
She was willing to tolerate the tantrums that her strictness brought about, and even the occasional remarks that Owen began to make about giving the girls their freedom. She became cautious, worrying about the effects that Natalie’s loud music might have on Cara; she found herself admonishing hysterical laughter.
She couldn’t hold it back forever. One evening, while she and Owen were clearing up the kitchen, Cara came in.
“I’m getting fat, Mum.”
“No you’re not, love.”
“I want to get fit.” Teresa drew in a breath. She looked significantly at Owen, and then realised that he wouldn’t understand.
“I was thinking of going swimming. They’ve got a session at the pool a couple of afternoons a week. I could go with Louise.”
“No,” said Teresa, “I don’t think that would be a good idea.”
“Why?” Cara’s face was red. “Why can’t I go? Other mums would encourage me to take some exercise.”
“It’ll get in the way of your homework.”
“No it won’t. I’m always finished by six; I spend the rest of the evening in my room. I’m bored.”
“I said no.”
Teresa felt hot, desperate. She was conscious that Owen was looking away, avoiding the discussion. Natalie, who had been reading a magazine in the living room, suddenly appeared at the door.
“Why won’t you let her go? It’s stupid. It’s not like she’s asking to go out and smoke crack!”
“This is none of your business, Natalie.” Teresa sensed a mutiny. She turned to Owen. “Tell them why this is not a good idea.”
Owen put his hand on Teresa’s shoulder. “To be honest, I see no harm in it, love,” he said.
“Yes!” said Cara, clenching a triumphant fist. She gave Teresa a sly smile, and hugged her father.
Teresa returned to the washing up. Thanks a lot, she muttered under her breath.
Perhaps it would be alright. Perhaps the link had gone, after all these years. Perhaps it was time to stop meddling.

*

When Natalie awoke the sun was streaking through her curtains, and the house was silent.
She felt a rush of panic. It was already morning. She had to get into the bathroom. She could see the lake from her bedroom window; in the bathroom, the glass was frosted. From in there, she could only hear Cara’s swim. Just like the first time. She didn’t want to risk seeing it.
She struggled out of bed and unlocked her bedroom door. On the landing was a plate with a slice of toast, cleaved into identical triangles. She stepped around them, and across the landing and into the bathroom, where she slammed the door, and reached out the slide the bolt into place.
Her hand met bare wood; there was nothing there but four fresh holes where screws once had been.
Taped to the back of the door was a note from Owen:
I’ve removed the lock. You can’t sit in the bathroom all day.

*

Cara fell in love with the pool. With Owen’s permission, she started going twice a week after school, and then, later, on Saturday mornings as well.
For Cara, swimming became an escape, a meditation. She loved the first push off from the side of the pool, with her arms stretched out in a point in front of her, her body in a stiff, straight line.
She loved the perfection of frogged legs kicked out and arms arced, of hands pressed together at the top of the stroke like a prayer, like namaste.
She loved the bodily whoop of butterfly stroke, the way it made her feel elemental, like a wave, a sonic boom.
She loved the sun making wrinkles on the tiles at the bottom of the pool in the mornings, and the halogen lights making haloes around her shadow in the evenings.
She loved that it got her out of the house, away from Teresa and away from Natalie.
She began to grow stronger, using weights and floats to build up muscle tone, pushing herself harder, adding extra lengths to every session. She began to do warm-up exercises by the side of the pool before she started, and stretches afterwards. She began to go on her own when Louise wasn’t in the mood. She began to know the faces of all of the lifeguards.
One afternoon, as she got out of the pool, one of them came over to her and introduced himself as Steve. He was short and had hair that was gelled into two crisp curtains either side of his forehead, but Cara liked the way his eyes were a deep milky blue. He asked Cara if she’d like to meet him in the café when she’d got changed. He bought her a hot chocolate in a plastic cup, and he smiled whenever she smiled.
That same afternoon, as she was walking back from school, Natalie felt a pain in her wrist. She didn’t know why. She nursed it all the way home. By the next morning, her knees, back, shoulders and ankles had joined in. Teresa let her take the day off school.
As Natalie was lying in bed, feeling strangely nauseous, every muscle in her body aching, Cara was sitting on the edge of her bed, her stomach churning with excitement. She didn’t tell anybody, especially not Natalie.
Instead, she packed her books into her school bag as she did every day, arranged her hair into a tight ponytail, and slid a pair of neat studs into her ears, but despite the comforts of her routine, she kept finding that a smile - a big, ridiculous one - had crept across her mouth. She knew that it wouldn’t do for Teresa to see it, and so, by way of a catharsis, she took her pristine homework diary back out of her bag, opened the front cover, and wrote Steve in tiny letters underneath her timetable.
This still didn’t stop the smile, so she had to leave without any breakfast, claiming that she had an early prefects’ meeting.
Teresa barely noticed anyway, because she was too busy wondering what on earth was the matter with Natalie.

Cara had to wait two more days until she was due to go swimming again, but she knew better than to arouse suspicion by asking to go more often. She sat the time out patiently, plotting exactly how she would look on Thursday when she arrived at the pool; imagining Steve asking politely, courteously, for their first kiss; dreaming a scenario in which she was drowning in the deep end, so that he had to dive in and rescue her.
On Thursday morning, Natalie didn’t even try to get up, and so Cara had to knock on her door to borrow some waterproof mascara. She drew Natalie’s curtains, making her sister groan and roll over to face the wall, and leaned in to the mirror so that she could drag the brush over her eyelashes, so that they were black and spindly.
“What’s wrong with you, Nat?” She wasn’t sure she liked the effect; it made her eyes look painted open, like a doll’s.
“Go away.” Natalie lifted her top pillow and buried her head underneath it.
“Have you got behind with your coursework or something? There’s obviously nothing wrong with you.” She blinked into the mirror. The lashes were somehow untidy; they spilled onto her face in an ungainly tangle.
Natalie didn’t reply. She had clamped a hand over the pillow so that her ears were blocked. Cara moved towards her to snatch the pillow away and shout into her ear, but as she got closer, she could see that Natalie’s hand was shaking. Cara stepped out of the room, and closed the door quietly. Perhaps Nat was sick after all. She hoped that Steve wouldn’t notice the eyelashes.
Downstairs, she waded through the tumble dryer for her swimming costume and a clean towel. She folded them, and put them into the bag that held her goggles, bathing cap (although she thought she might not wear it today), shampoo, conditioner and shower gel. Teresa was standing by the cooker, making sandwiches.
“Perhaps you should miss swimming tonight, love,” she said, “seeing as Natalie’s ill.”
“It’s not like it’ll make her any better if I don’t,” said Cara, and she left as quickly as she could through the back door, leaving Teresa staring at the space where she’d been.

*

It’s nearly time.
Natalie began to look for the missing lock. She emptied the cupboard under the sink and turned the washing basket over, but she could find nothing. The sun was already high; it was dazzling through the patterned glass, and the room was getting hotter.
It’s nearly time.
Natalie considered for a few moments that she could just take a bath without a lock on the door; but then she felt afraid that they’d be monitoring her now, if they’d gone so far as to take the lock off. If she couldn’t put it back on the door, then she’d have to find some other way to keep them out. She felt dry, stale in her towelling gown and slippers; she was filled with an urge to submerge herself in water, to be clean again.
It’s nearly time.
She had to do something quickly, before Cara came. She couldn’t risk being anywhere else. She felt her throat tightening with the thought of missing the whole thing, or, worse, of Cara knowing that Nat wasn’t placed, just so, waiting for her, and so not coming at all. After all, the bath, the early morning sunlight, the open window - they were all part of it, weren’t they? Part of the trick she played every sunny morning to conjure up her sister’s ghost. If she didn’t do those things, would anyone remember?
She was crying now, grizzling little words to will herself along. Chair, chair, chair, she said, as rushed across the landing into her mother’s room to find something to wedge the door shut; and then, he doesn’t understand. He wasn’t there.

*

After a week, Teresa took Natalie to the doctor. She was sick in the car on the way, but they were nevertheless told that it was probably just a virus. Teresa disagreed. When things didn’t improve after another week, she drove Natalie back to the surgery and asked for blood tests.
In the meantime, she tried to find a way to stop Cara from swimming. She looked desperately for an excuse to ground her, but found none. She left Cara’s swimming costume at the bottom of the laundry basket, damp and unwashed, but Cara rinsed it and packed it wet. She even tried to suggest to Owen that Cara might bring germs back from the pool that would make Natalie worse. Nothing worked, and Teresa was sure that, whatever happened, she could never tell Owen the truth. It was all too irrational. He would never believe her.
Little did Teresa know that Cara had given up swimming altogether. Every opportunity she got to go to the pool would be spent standing next to Steve as he did his work, or, if his supervisor was busy, sneaking into the office with him, so that she could sit on his lap in the big swivel chair and kiss him. Sometimes, if he was on an early shift, he would already be finished by the time she came out of school, and they would sit in the poolside café, drinking hot chocolate and talking. Whatever they did together, she always remembered to dip her swimming costume in the chlorine footbaths by the changing rooms and to wrap it in her towel before she went home.
Subterfuge didn’t come naturally to Cara. She was an uneasy liar, and despite the fact that Teresa and Owen seemed almost completely absorbed in Natalie’s problems, hoodwinking them made her feel untidy, disordered.
More than that, she was proud of Steve. He was nineteen, well-spoken, and taking a gap year before university. She was in love, and was full of fantasies of her future life with him; about marriage and children. She imagined herself with twin girls, just like her and Natalie.
She had to tell her parents. She was sixteen - why shouldn’t she have a boyfriend? And besides all of that, Steve had no idea that he was a secret.
So, one Friday afternoon, when Teresa, Owen and Natalie came back from a mob-handed visit to the doctor, they found Cara and Steve sitting on the sofa as if it was the most ordinary thing in the world. This was the best way, Cara reasoned. Nobody could say anything if they were presented with a fait accompli.
She was wrong, of course. As soon as Natalie saw him her nose began to bleed, but she laughed anyway, her hand over her face, as she rushed to the bathroom to find some tissues.
Cara stood up. “This is Steve,” she said. Steve stood up too, and offered his hand to Owen, who shook it. He then turned to Teresa.
“Get out!” she said. There was a nauseous silence in the room, as if everybody was absorbing her words. Steve’s hand hung in the air for a few seconds, before Cara pulled it to her side, and looked to Owen for help. Her father sighed jaggedly and said, “Terry…”
“How dare you bring him in here like this? Get him out!” Teresa grabbed Steve by his other arm, and began to drag him to the door. He shook himself free, took his coat, threw a last glance back at Cara, and left.
Teresa was crying now; her face was red and she was shaking. “What on earth were you thinking bringing him here with Natalie in the house? How long have you been with him? No wonder she’s been so ill!”
Owen rested a hand on her back, but she shrugged it off. “Terry,” he said, “what’s all this about?”
And Teresa couldn’t think of any other way around it, so she told him everything: about the baby who had needed to be fed less so that her sister could grow, about the little girl whose ballet lessons made her sister sick, about the care that Teresa had taken, for the last sixteen years to strike a balance for the two of them, to keep both their lives smooth, flat, without ups or downs, so that both of them could have a chance.
As she spoke, Natalie watched her from the doorway, a wad of tissues pressed to her face, and Cara sat on the sofa, staring at her. Owen just shook his head, over and over again, and rubbed his hands hard over his face; from time to time, he looked swiftly around the room, as if he was trying to find an escape route.
“This is ridiculous,” he said finally, when Teresa could think of no more to say, “you’ve concocted this whole story in your head over the years, and you can’t let go of it. You’ve never forgiven Cara, have you, for being stronger?”
“No,” said Teresa, “that’s not true. I’ve just been trying to strike a balance. I’ve had to.”
“She’s right,” said Cara, who had been watching everything impassively. “It makes sense; I don’t know why.” She went over to the doorway where Natalie was still standing. “I’ll finish it tomorrow, Nats,” she said.
“You’ve all gone bloody mad,” said Owen.

*

Natalie carried the chair from Teresa’s dressing table into the bathroom, slammed the door shut, and pushed the back of the chair up under the handle, before going over to the bath and putting the taps on full.
She held her head down there for a while, letting the rush of the water fill her ears, and said aloud, “you can’t come yet; I can’t hear you.”
Then she thought that she ought to block her ears to make sure, and so she went over to the mirror cabinet and began to stuff them with cotton wool. The bath wasn’t even a quarter full. “You can’t come yet,” she said again, and she sat on the edge of the bath, her clothes sticking to her as the steam rose. She tried to picture her sister’s face, but found it hard to pin down the features, even though they were her own.
And then her eyes fell upon the chair. It looked absurd, propped there, its curled iron back barely touching the door-handle. It wouldn’t work. If they wanted to come in, they could. The chair would just slide across the damp lino if anyone pushed the door. It was useless. She couldn’t take a bath like this. And anyhow, Cara wouldn’t come unless the details were right.
She would have to screw the lock back on. It would be in the garage, with Owen’s tools. Perhaps Cara would hold back, just for a while.
Natalie pushed the chair out of her way, and ran down the stairs.

*

Cara gave up Steve and swimming the next day. She told herself that she was a practical sort of a person, that she was capable of making the necessary sacrifices. She worked hard at school, and, in the evenings, she worked even harder at becoming friends with Natalie, who got better so quickly after Cara gave up her secret life that even Owen wondered if there wasn’t something in it. Ultimately, though, he concluded that Natalie’s illness must, as the doctor had told them, have been the result of an unidentifiable virus that had gone away as swiftly and as mysteriously as it had arrived.
As Natalie began to regain her colour, Teresa felt a wonderful sense of fellowship. It was as if, after all the years of making clandestine interventions into the twins’ lives, she had finally been vindicated, and in the process, had gained an assistant, in the form of Cara, who was actively restraining her own life in order to help her sister. Natalie seemed not to have much to say on the matter, but then, reasoned Teresa, why should she? None of this was her fault. The whole episode (and in fact, she now realised, many other episodes like it over the years) had been caused by Cara and her little deception, and so it was up to Cara to make amends. Natalie needed only to get better.
Natalie herself felt only dazed. All she knew was that she had been well, and then bewilderingly ill, and then well again in the space of six weeks. She found it hard to believe that this could be any responsibility of Cara’s; and even if she could believe it, she was not sure that she liked the implications that it carried.
It had been years since the pair of them had spent any time together, but now Cara seemed to be trying to jump-start a bond between them. She would sit in Natalie’s bedroom and flick through her CDs, or bring Natalie armfuls of clothes from her own wardrobe, wanting her to try them on.
More than that, Cara seemed to be struggling to fill her time now that she could no longer go to the pool. She had worked out an elaborate exercise regime of sit-ups, stretches and sprints up and down the stairs that she performed every afternoon when she got in from school; she went through all her school files and typed up the notes, adding diagrams and illustrations that she found on the internet; most evenings, or so it seemed to Natalie, she would sit at the dining table and wipe off all her nail polish, methodically manicure each fingernail, and then reapply the enamel in slow, deliberate strokes.
One night, about a month after this all began, Natalie watched Cara sitting in the living room. It was ten o’clock, and she had already gone through the exercises, the typing and the manicure. She sat in an armchair with a book balanced across her lap, and tried to follow the text with her finger, but it was clear that she was taking nothing in as she had been on the same page for the last half-hour; every time her finger reached the bottom of the page, she would look up, sigh, and start again at the beginning. Eventually, she just sat and stared into the wallpaper. She was still doing this when Natalie went to bed.
Natalie brushed her teeth, pulled on her pyjamas and tried to make herself comfortable, but she couldn’t seem to settle. However she lay, she could feel her heart beating so hard that it seemed to push the air out of her lungs. In time, she heard the rest of the household, one by one, coming up the stairs, using the bathroom and getting into bed, but long after the house was still and silent, she still couldn’t seem to fall asleep. She began trying to count her breaths, making each one calmer, deeper, but she never got above five before the picture of Cara staring at the wall found its way in to her mind, like interference.
There was a creak of floorboards on the landing, and her door opened.
“Are you awake?”
Natalie sat up and drew the curtains so that she could see her; at night, the lake was floodlit, and so Cara’s face was turquoise in its reflected glow. She lifted the duvet and got in beside Natalie, who tried not to flinch at the touch of this unfamiliar body.
“I can’t do this,” said Cara. “I’m doing my best, but I can’t bear it.” Her voice was calm, serene, but her face glittered with tears.
“I know,” said Natalie, “we’ll talk to Mum in the morning.”
“No. It’s no good. She’s right. I’d just make you ill again.” Her voice convulsed into gasps. “It’s no good.”
Natalie put her arm around Cara, and kissed her wet cheek. The sight of an identical face so close to hers made her feel squeamish, as if her own unhappy ghost was laying beside her. “You don’t believe all that stuff, do you?”
“I think I do.”
“But then, what’s the solution? That neither of us ever have a life?”
Cara took a deep, unsteady breath. “Maybe there wasn’t supposed to be two of us. I’ve read about identical twins. We’re a mutation. We start off as one person, and end up two.”
“So what? We’ve not ended up the same person. We’re completely different.”
“We’re two sides of the same coin.” Cara rolled over and turned her back to Natalie. “Let’s not talk any more.”
Natalie turned towards the window so that she could feel her curved spine touching Cara’s, and felt herself be dragged into sleep.

When she awoke the next morning, her head was full of her sister’s dreams: heavy, blue, watery. The bedroom was hot and the early morning sun was beaming round the sides of the curtains, making Natalie’s eyes water. Cara had already gone; she didn’t even need to turn over to check that. Natalie knew exactly where she was, what she was doing; her dreams had told her.
She pulled back a curtain, and, wincing against the harsh light that dazzled off the surface of the lake, watched her sister scrambling down the scrubby bank, her swimming bag on her back.
There, at that moment, it would have been easy to stop her. Natalie opened the window to call out, and its creak made Cara turn. She stared up at the window for a few seconds and then batted her hand at Natalie, as if to say, go away, look away. Natalie found she couldn’t speak; she was anchored to the spot, her mouth silenced. She could feel, coursing through her, Cara’s determination, her sense of rightness, her resignation. She shut the window and sat on the edge of the bed, the pain and nausea of the last months seeping back into her as her sister came alive under her task.
Natalie didn’t want her sister to die, but she wanted to see it even less. She closed her bedroom curtains, but it somehow wasn’t enough, with the clear blue light creeping into the room, so she ran across the landing and into the bathroom, where she pushed the plug into the bottom of the bath and turned the taps on full. As the roar of the water filled her ears and the steam began to rise, she vomited into the sink, and then slumped down by the side of the bath, imagining, against her will, Cara’s slow progress down the bank, under the fence at the point where the foxes had burrowed, and down the final chalky stretch to the lake.
By the time the bath was half-full, Natalie knew that Cara must have already reached the water. She tried not to think of her fighting the heavy undertows that rumbled under the lake’s surface. She tried not to think of her face disappearing under the chalky blue, the face that, at the end, was Natalie’s after all, and always would be.
After a while, Natalie could hear the overflow of the bath begin to gurgle. She knelt up and reached for the taps, but her hand was reluctant, afraid of losing the oblivious white noise of the water in full flow. By now, she thought, she must be gone. The bathwater was lapping nearly to the top, so she turned off the taps and eased herself in, shuddering at the splash of displaced water onto the floor. She drew in a deep breath and floated onto her back, her head submerged. She opened her eyes and watched the sun making wrinkles on the surface of the water. She listened to the ominous boom of her heartbeat, alone. She savoured the airless ache in her lungs and understood the impulse to draw in a last, drowning breath. She came up panting, her head spinning.
The bathroom was silent. Natalie leaned her head against the back of the bath and felt the sadness settling in, weighing down on every limb.
Then, she heard a splash. She sat up, the water slopping again over the floor, and strained her ears towards the window. The sound of a strong, slow breast-stroke came drifting into the bathroom, its gentle rhythm as easy as breathing. Natalie felt a ball of shock melt inside her chest, and slide down through her stomach, her legs, her feet. Cara was making it. She was swimming against the water. It was all a lie, about the chalk and the currents, the drowned children, the drowned adults. It was a myth, a fairytale. Cara was conquering the lake. Natalie imagined her sister gliding to its centre, frogged legs kicked out and arms arced, hands pressed together at the top of the stroke like a prayer, like namaste…
The was a splash, only a slight one, the sound of a pair of legs kicking against the water, struggling to keep in time. Natalie willed Cara to stay afloat, synchronised her breath to the rhythm of the strokes, but she couldn’t up. She could hear Cara’s arms getting slower, heavier, the rush of water getting weaker each time she pushed back against it.
Soon, no sound came at all, except for a tiny gulp that Natalie thought she heard seconds before a light went out inside of her.

When they told Natalie that they’d found Cara’s towel and clothes folded neatly at the side of the lake, but could find no trace of her sister, she found herself crying as if she didn’t know.

*

Natalie gripped the banister and hurled herself down the stairs, her feet pounding fast against the hollow wood. She had to get the lock, get back to the bathroom, be ready for when Cara came. She misjudged the dog-leg halfway down, and ran heavily into the wall, reeling back off of it towards the handrail. Her foot slipped, her legs flew out in front of her, and she found herself sliding down the stairs on her back, the carpet burning her skin.
At the bottom, she sat up, buried her face in her hands and began to spit out jolting tears, her face hot with the pointlessness of what she was doing. She would never hear Cara again now; she had lost her. She raked her fingers through her hair and dug her nails into her scalp as her whole body convulsed.
Then, the light changed.
Natalie looked up, strained to listen for it.
It came. The sound of strong, careful strokes drifted into the stairwell.
Natalie stood up. From where she was standing, she could see the blue light sparkling against the walls of the living room. Perhaps today everything was different. Perhaps it was time for a change.
The strokes were already getting weaker. Natalie carried herself, footstep by footstep, into the living room, her knees unsteady, boneless.
The curtains were drawn back, and the lake spread out before her, its waters glowing, translucent. At first Natalie could see nothing, but as her eyes adjusted to the smoothness of the surface, she began to see a fault in it, and then a tiny figure moving across it, leaving a white trail behind her like a scar.
She pressed her fingers against the window pane and leant into it as she watched what she had been hearing for a long time: the little figure’s arms slowing, weakening, the head dipping under, coming up, gasping, dipping again. A face breaching the water. And then nothing. The waters smoothing over, forgetting.
There was a small sigh behind Natalie. She spun round, and there, sitting in a chair, watching over the lake, was her mother. Her face was a grainy white, streaked with tears. She held Natalie in an unblinking stare.
“You’re not the only one who sees her, Natalie,” she said. “Only on sunny days. Just like the first time.”