Claire is bitten terribly. Her legs and feet are covered. A bite on her eyelid causes it to swell so that she can hardly open her eye. The mother purchases Benadryl at the resort shop and Claire spends the day in a groggy haze, scratching.

Alison takes her sister’s hand and pulls it away. “Don’t.” She presses her palm to her sister’s skin. For a brief moment Claire is soothed. “Poor Clairey. You’re just too sweet.”

DURING THE last days of vacation, adults begin to speak of their return.

“When we get home, remind me to take the car in.”

“Let’s be sure to call the Vitales about dinner.”

“Don’t let me forget to sign the boys up for Little League.”

The sisters’ parents are no different. Two days before their departure, as they lie on the beach, the mother remembers that she has unread library books, by now overdue, on her bedside table. When they get home she will return them and take out new ones, and this time she will actually read them. This vacation has reminded her how much she loves to read. The father announces that when they get back he will start going to the gym in the morning before work like he used to, no excuses. They are energized. Excited, even, to be off this island and back home, where their plans can be implemented, this energy put to use. The vacation has served its purpose—it has made them eager to be home.

A few days ago, they imagined leaving their jobs, their houses, their lives behind and moving down here. Some of them even spent an afternoon viewing properties with a Realtor. Now they see that they were simply indulging a fantasy that, like most fantasies, is not something they actually want. They would grow bored here. The bright colors would grate on their eyes. The sound of the ocean would torment them.

GUESTS DEPART daily. The resort shuttle takes them in reverse, up the palm-lined drive, onto the rutted public road, past concrete houses, roosters and goats, clothes on clotheslines fluttering over sandy yards. At Sir Randall Corwin International Airport, they walk back across the tarmac, up the stairs onto a plane, speed back down the runway, and lift into the sky. They touch down in Boston or New York or Chicago amid a papery snowfall and drive the dark roads home.

Inevitably, they leave things behind—in their rooms, by the pool, buried in the sand. The staff gathers these objects at the lost and found, but they are rarely claimed. Once a month, Gwendolyn from the spa drives the items to Bendy Harbour Baptist Church. A gold necklace with an amethyst pendant. A denim jacket. A red shawl. Infinite sunglasses. A camera (the roll of film inside never to be developed). A legal thriller. A wristwatch with a green face.

ON THE day before they return home, Alison, Clairey, and their father walk down the beach to where the local woman who braids hair sits beneath a faded blue umbrella. Their father hands the woman sixty dollars, takes a picture of the girls (the woman looking up briefly—humorlessly, the father thinks—from combing Claire’s fine white hair), and returns to his lounge chair.

As the woman braids Claire’s hair, the sisters sift through the basket of beads, picking out purple and white.

“I’ll come back to check on you,” Alison says. She pecks her sister on the forehead and is off.

The braiding takes nearly two hours. The woman does not try to get her to talk, which is a relief to Claire. She likes sitting here, the silence and the feeling of the woman’s hands working quickly yet gently through her hair. The sun is hot, the bites on her legs beg to be scratched, but she stays still, fortified by an image of herself returning to school with these braids, the beads tinkling as she walks, and how, for a rare, brief time, the other girls will envy her.

When the woman is finished, she hands Claire a clouded plastic mirror. It is better than she dared hope.

The woman looks at her. “My, you a patient child.”

THAT NIGHT, Claire claws through her sleep. No matter how she scratches at the bites, she can’t make the itching stop. All night she tosses in and out of dreams. When she wakes up it is dawn, barely light. The bites on her legs are crusted with dried, rust-colored blood. The blood has stained the crisp white sheets, too, blots so perfectly red it makes her dizzy. She looks around the room. Alison is gone.

WHAT DO a mother and father do when they are awakened by one child to the news that the other is missing? First, they tell themselves not to panic. Their daughter must have simply gone off somewhere on the resort grounds. It is a large property and there are any number of places she could be. Perhaps she has gone for a jog, or to smack tennis balls against the backboard at the courts. The small red blip of a kayak far out on the water might be her—maybe she decided to squeeze in one last water sport before their departure. Perhaps she got too drunk at the hotel bar last night and is sleeping off a hangover in the room of one of the other girls her age. (The parents are not na?ve; they know that a teenager is apt to have one daiquiri too many after her parents have gone to bed on the last night of a Caribbean vacation.) Surely she will come groggily across the sand anytime now, and how furious they will be! And how pleasurable it will be to be furious with a daughter who is perfectly fine, and who will be snotty and dismissive when they tell her how worried they have been.

But she is in none of these places doing none of these things. By late morning, a mother and father’s faith that their child will turn up any moment has given way to terror. Everything but Alison is forgotten. Breakfast, lunch … Claire is starving but says nothing.

Word spreads quickly among the guests.

“Did you hear? That pretty girl with the auburn hair is missing.”

“The one with the scar?”

“They’re saying she never came home last night.”

The police are summoned. The chief of police asks the mother and father a series of questions, and they tell him about their vacation in precise, dutiful detail. As guests sun themselves by the pool and climb the StairMaster to oblivion in the fitness center, the Royal Police Force of Saint X combs the property. The time for the family’s flight home comes and goes.

ON THE first night after Alison’s disappearance the sunset is the most beautiful yet, a flashy display of scarlet and violet that deepens, as the sun slips below the horizon, until it is the shade of a bruise. On the balcony, a mother watches the sun go down, then sinks to the floor. She crouches on hands and knees and dry-heaves over the cool terra-cotta tiles. A father goes to her, holds her. He tells her that everything could still be okay. She repeats this. Everything could still be okay. Hearing these words echoed back to him from his wife, a father breaks down. They remain on the balcony, intertwined, for some time. A sense of distance from the day’s events comes over the mother and she wonders, with detached curiosity, whether she is becoming—whether she is already—the one thing none of the mothers ever want to be. A father is seized by the most unaccountable memory: Alison, one year old and bald as could be, blowing raspberries against his cheek.

From inside, where she has been set up in front of the television, Claire watches her parents. Later that night, they put her between them in their bed. In the middle of the night she wakes to the feeling of a hand on her back; for a moment, she thinks it is Alison. Then she remembers. It is her father’s hand, checking for the rise and fall of her breath. Claire lies awake, eyes wide open in the dark.

ON THE second day, the chief of police asks the mother and father to take him through their time on the island once more. The father tells him again about their arrival, ten days ago, on a TWA flight out of Kennedy. Alison slept late the next morning. She drank a fruit punch.

“He was after her all week,” the mother interrupts. Her body trembles. “That blond boy. He couldn’t leave her alone.” As she speaks, a film reel of horrible possibilities flickers through her mind. She’d liked this boy, found it sweet the way he lingered, at once cocky and unsure, around her daughter. What if she’d misjudged him? What a fool she’d been, thinking herself a good mom, a fun mom, for letting her daughter go off with him. How had she allowed herself to forget that in the end a mother has only one job? Suddenly she cannot breathe. The warm tropical air clogs in her throat. When she begins to hyperventilate, the chief of police calls for the hotel doctor, who arrives promptly, examines the mother swiftly, and writes a prescription for a sedative. A porter is sent to the local chemist’s to collect it. The doctor pulls the father aside. “I might suggest that you have a babysitter called for the little one,” he tells him quietly, gesturing at Claire, who is sitting in a wicker chair, eyes on her mother. “Give yourselves some time and space.”

“If you think we’re going to let our daughter out of our sight, if you think we’re going to leave her with some person who could be anyone, you’re out of your mind.”

“Of course. I apologize.”

“Everyone here could be anyone. You could be anyone.”