Six years ago, on this very day, at this very beach, a young man rose with the dawn, crawled from his tent, stripped naked, and pulled on his wet suit. He did not attempt to wake his friends, all recent Class of 2000 high-school graduates from Michigan who, to mark their final days together before heading off to college, had piled into a couple of cars and driven nineteen sleepless hours to this state park on Florida’s Treasure Coast. A week later the boy’s father would read a newspaper interview with one of those young people, a girl who had never camped before and kept startling awake at the slightest sound. According to the report, she’d heard the young man curse under his breath as he’d tripped over a trash bag full of empty beer cans. Peeking out through the mesh of her doorway, she watched him gather his surfboard and stroll off with long, lanky strides, his impressive muddle of curly brown hair bouncing ostentatiously as he made his way toward the beach. Because the campground overlooked the water, she could see him wade in, climb onto the board belly-down, and paddle out into the waves. Then, as the girl would explain in that interview, she lost sight of him, his silhouette disappearing into the first fierce burst of sunrise.

Although the father has known this young woman since she starred with his son in an eighth-grade production of The Lion King (the boy as a pimply Mufasa, the girl as Rafiki, badly off-key in “Circle of Life”), they’ve spoken only a couple of times since the incident. She seemed scared of him, as if he might somehow blame her for his son’s disappearance — no corpse, no clues, even the surfboard gone without a trace. And perhaps he does blame her: not just for surviving; not just for telling her story to reporters before she recounted it (in less detail) to him; not just for having no answers; but for moving on while his life stands still. The girl who played Rafiki is in law school now, while he and his wife are back on this same beach with their fifteen-year-old daughter.

Unlike the sweltering day when the boy vanished, this morning is chilly, a dense fog giving the coastline the dreamlike appearance of a faded photograph. Nothing has substance except the iodine smell of the sea, so potent it seems to dull his other senses, lulling him into a waking dream. One moment, his wife is standing right next to him on the beach. The next, without an instant appearing to pass, she’s wading into the water fully clothed.

“I see something,” she says.

“Where?” her husband asks.

“Out there,” she replies, pointing into the gray haze.

The man stares into the mist but can’t make out anything besides slow-rolling waves. Then it occurs to him that his wife probably doesn’t see anything either. He turns to his daughter, who sits on a dune, yanking handfuls of seagrass from the sand. She glances up, bulky headphones clamped tight over close-cropped hair, iPod blasting some punk band so loud he can hear the tinny throb ten yards away. Then she rises and trudges toward him in the black leather jacket and beat-up combat boots she wears almost everywhere. Nine years the missing boy’s junior, she’s as inward as he was extroverted, as apprehensive as he was carefree, as unsure of herself as he was brash. As she comes close, the man feels a sudden desire to reach out and embrace her, but she just gives him an angry glare and marches past, down the beach.

“Good luck,” she says over her shoulder. “This year he’s sure to show up.”

“Don’t be nasty,” he says, but she just keeps walking.

His wife is now knee-deep in the surf, her jeans and cardigan blending into the fog. In this amorphous state she seems somehow smaller and more fragile, and it occurs to him that perhaps what he sees is no optical illusion. Although she’s good at keeping up appearances, his wife has always been restless, painfully unsure about her place in the world. He comes from a close-knit family, but she’s the only child of an unhappy marriage. Her father left when she was a toddler — one final abandonment for her mother, who’d been raised in a series of foster homes after her parents had died in the concentration camps during World War II. This lonely upbringing had left the woman with little aptitude for, or interest in, raising a child. As a result the man’s wife was denied something that most children get; something that makes the world seem solid. Love.

He wants to run to her now, take her by the hand, and lead her back to shore, but he’s always been afraid of water, a phobia that goes back to swimming lessons at the YMCA on the corner of West Maple and Hudson Street in Kalamazoo, where, at the age of six, he would pee in his swim trunks while waiting in line for the instructor — a huge, gruff man with a hairy back — to throw him into the pool. This terror has only intensified since his son’s disappearance, especially today, when the water seems to be pressing in on him from the air as well as the sea. He takes a couple of steps toward his wife, then stops, paralyzed by the sight of the surf licking at the sand. Short of breath, he watches his spouse dissolve into a curtain of vapor that gives him the sensation of teetering on the edge of a void. This woman, who works at the circulation desk of the public library and serves as secretary of the local League of Women Voters; who sleeps next to him every night and starts the coffee every morning and drives their daughter to school, orthodontist appointments, and visits to the therapist; the same woman who was just standing on solid earth is now somehow an apparition, both present and absent, there and not — just like the melody he now hears emerging from the mist, a wordless tune, beautiful and haunting, that his wife sometimes hums when she’s anxious or excited or deep in thought and thinks he’s not listening.

Kicking off his sandals, he wills himself into the water, but the cold surf shocks him like a live wire, jolting his whole body and causing him to leap back. Wheeling around, he sees that his daughter, too, is fading away. He calls her name, but she doesn’t respond, just stomps off through the mist as if trying to bully it into lifting. In those first few months after the boy’s disappearance, his wife had doted on the girl, not even letting her out of her sight at bedtime, when she’d sit in her room for hours, watching her sleep while humming the same mournful tune he’s hearing now. But over the years he has sensed his wife slowly pushing their surviving child away. It’s not anything she says out loud, just a coolness that has slowly grown into a kind of unspoken antipathy the girl can’t help but feel — and return. On public TV not long ago he saw a documentary about Doggerland, the name for some underwater terrain that once connected England and Northern Europe before rising ocean levels submerged it almost eight millennia ago. Now, as he watches his daughter vanish in one direction and his wife in another, he thinks whatever it was that once held his family together has long since gone the way of that doomed landmass, swallowed by the sea.

At his feet a sand-colored crab skitters on hairy legs, moving sideways, then backward, before suddenly shooting away as if in panic. The man can barely make out his wife, a smudge in the mist, the waves by now above her waist.

“Can you see what it is?” he shouts.

“No, but I feel it.” Her voice sounds far away.

“Feel what?”

“It’s here. I can almost touch it,” he hears her say. Then there’s silence. Then the song. The sea air feels suffocating. Why do they keep making these annual beachcombing pilgrimages? What do they hope to find? Most of what they pull from the surf is just junk — soda bottles, cigarette lighters, polystyrene food containers, running shoes, tennis balls, fishing nets, buoys, wooden pallets, and oil drums. But once, they found a plastic bride-and-groom figurine from a wedding cake, paint scoured off by the ocean, facial features eroded. Judging by the hair and clothing styles, the figurine could have been fifty or sixty years old. Where had it come from? How long had it been floating around? And what had become of the real wedded couple?

He can no longer see his wife. All that remains of her is the song, which seems to rise above the sound of the waves, as if from the fog itself, everywhere yet evanescent. In the early years of their marriage he used to ask her about this haunting melody, which sometimes reminds him of a lullaby, sometimes of a dirge. She would just shrug. There are so many things she keeps to herself, so many things he doesn’t understand. It was not normally like her, for example, to wade into the water with all her clothes on. If anything, his wife of twenty-three years has been rational and fastidious to a fault. But ever since their beachcombing began, she’s become increasingly impulsive. Last year the two of them were strolling the shoreline on a windy, overcast afternoon when, without a word, his wife turned and splashed into the crashing waves. She came back a few minutes later, soaked to the skin, cradling something in her arms like an infant. Just more driftwood, the man assumed, but as she came closer, he saw that the thing was man-made, a lathed cylinder about three feet long with spherical shapes on each end, like an old-fashioned dumbbell. And as his wife reached the shore, shivering and breathless, he could make out that the piece of wood had once been painted white with twisting blue and red stripes, now badly faded. The next day, while his wife and daughter were at the grocery store, he took the artifact to a local antiques dealer, who confirmed what the man suspected: the relic was a wooden barbershop pole, perhaps a hundred years old.

“But how is that possible?”

The dealer shrugged. “It happens,” he said. “Every so often the ocean coughs up some cargo from the deep that defies rational explanation. I don’t get too shocked about it anymore.” People had come into his shop with all manner of beachcombing oddities, he added: a tortoiseshell hair comb from the 1700s; a fully intact rolltop desk, circa 1910; a barnacle-encrusted piece of the Space Shuttle Challenger. And just last year, he said, the shipwrecked hull of a nineteenth-century vessel had suddenly appeared on a beach in northern Florida. The thing was huge — forty-eight feet long and twelve feet wide — with the ribs of its frame almost completely intact. But what was weirdest of all is it had seemingly come out of nowhere. There was nothing special about the water currents on the day it washed in, nothing unusual about the weather.

“Ever heard of the littoral zone?” the antiques dealer asked.

“Something to do with the shoreline, right?”

“Yes, sir. It’s the part that’s above ocean level at low tide and underwater when the tide is high. Not quite land, not quite sea. Anything is possible there.”

Now, shouting his wife’s name, the man forces himself into this same littoral zone, unsure whether his convulsions are from cold or fear, certain only that he needs to reach her before something terrible happens, something he should have seen coming. For the past couple of years she’s become obsessed with omens and revelations — crazy talk, dangerous talk, the kind of talk people engage in before they do something desperate. That’s why he didn’t return that barbershop pole to her. He’d originally planned to throw it back into the sea, but he couldn’t part with it when the time came. Instead he hid it away in the car trunk. When they got back to Kalamazoo, he told his wife that he must have left the pole in their hotel room back in Florida. There was a scene, and then there was silence, as thick and forbidding as the fog into which she has now vanished.

He brought the barber pole into the house, moving it from hiding place to hiding place, never sure whether he wanted to protect his wife from it or keep it to himself. Then he hit on an idea, irrational but irresistible, the impulse for which he still doesn’t completely understand. Using spare scraps of plywood, he built a rectangular box, lined it with velour, and fitted it with a lid, which he screwed shut after placing the pole inside. One Saturday, when he knew his wife and daughter would be gone, he rolled back the carpet in the master bedroom, pried up some floorboards, and placed the wooden box between a couple of joists. Now he and his wife sleep over it every night.

Occasionally, unable to calm his mind in the late hours, he feels as if there were a time bomb beneath him. But on most nights he finds it strangely comforting to know the box is there, his own private littoral zone between past and present, a secret from his wife. He wants to put his child to rest. Why had it taken him so long to understand that the thing he’d buried beneath their floor was a coffin?

For his wife the search for their son will never be satisfied. He’s sure of that now, shivering in the surf as that faint melody fades in and out. The air is so thick it seems to break up time, every second suddenly discrete, unconnected to the one before it. A young man out for a run emerges from the mist, staring straight ahead as if unaware of the man’s presence, then vanishes midstride. He tries to picture how his boy ran, how he moved. No image comes to mind. He listens for the sound of footfalls. None reaches him. He calls his wife again. Nothing. He pictures her walking slowly, steadily as the waves crash over her head and the sea consumes her. Is she capable of such a thing? He listens for the song but hears only the draw and push of his own breath as he splashes forward, tripping into the surf, soaking his clothes, feeling the unbearable weight of the sea on his skin. A plastic bottle floats past, its label in some language he doesn’t recognize. He thinks of the traces of Doggerland that keep showing up in fishing nets: a human jawbone, part of a skull, animal bones carved with mysterious zigzagging lines, flint tools, spear points, a whole world that still exists on the ocean floor.

Suddenly he can almost feel the ocean retreating in front of him, siphoning into some giant drain at the center of the world to reveal everything that’s ever been lost: Spanish treasure ships, their holds packed with silver and gold. Transatlantic sea liners and freighters and fishing trawlers and U-boats and luxury yachts with cases of expensive champagne still cooling in the refrigerator. Bottles stuffed with soggy notes that never reached the eyes of strangers. Wedding rings, bronze cannons, can tabs, antique brass compasses, shipping containers full of Barbie dolls and cell phones and vacuum cleaners and car tires and sex toys and packages of heroin. Endless items blown or thrown overboard. Mafiosos limping around with cement blocks on their feet and drunkards sleeping it off on beds of seaweed. Pirates and explorers and Vikings and long-distance swimmers and dirigible pilots and kite surfers and clumsy cruise-ship passengers, whole crowds of people sloshing around in the muck. And somewhere out there, still out of sight amid this vast jungle of wreckage, is his son.

Stumbling forward, the man screams, “Where are you?

“Where the hell are you?” he yells again.

He waits for a shout or a song from the thickening fog but hears only waves rolling under and under and back under, always disappearing into the sea.