The novel opens in 1970 as an unnamed man drives his Mercedes convertible onto the ferry to Packett Island. None of the islanders recognize him; he was barely 15 the last time he made the crossing, 28 years ago. As the morning mist lifts, he spots a cedar-shingled house on a high dune, a house he remembers nail by nail. He removes his shoes and walks barefoot along the beach, thinking of a woman he once loved: "Dorothy. I love you, Dorothy." Voices from the past cut through the fog, boys calling his name, and three young boys dash across the sand. He wants to be one of them again.
The narrative shifts to the summer of 1942. Hermie, the 15-year-old protagonist, spends the summer on Packett Island with his family, painfully caught between boyhood and manhood. His best friend, Oscy, is a month older, strong, and confident, the group's unquestioned leader. Their junior companion, Benjie, is the youngest and scrawniest, perpetually the target of Oscy's bullying. They call themselves the Terrible Trio.
Lying atop a dune, the boys watch a powerfully built man chop wood below a house. A beautiful dark-haired woman with green eyes emerges and kisses him. The kiss mesmerizes the boys with awe and confused arousal, and Hermie is particularly affected. The man is a soldier, and the woman is his wife.
Wartime pervades island life: Hermie's father visits only every other weekend because of gas rationing, and service stars, window banners indicating family members in military service, hang throughout the neighborhood. Hermie fills his days saving toothpaste tubes for the war effort and listening to radio serials. On the beach, the Terrible Trio bicker and stew in boredom. When the soldier and his wife stroll past, Hermie surprises his friends by commenting on the woman's figure, revealing a fixation that deepens all summer. At the ferry pier, he watches the soldier depart in full Army uniform, captivated by the couple's long farewell kiss.
Tensions boil over when Oscy pushes Hermie toward the sunbathing woman, daring him to say hello. Hermie circles her but cannot speak, and when his friends shout crude warnings, he flees. Oscy tackles him, triggering a genuine fight. Hermie, usually outmatched, keeps getting up and lands a solid punch on Oscy's nose before being knocked out. The fight ends with grudging mutual respect, and Hermie walks home feeling better than he ever has.
Days later, Hermie spots the woman struggling with grocery bags and rushes to help. She is gracious and sunny; he is nervous and eager to seem mature. He carries her bags home, scalds his tongue on her coffee, and fabricates details about his life. On the mantel he notices a framed photo of the soldier inscribed "All my love, forever, Pete." When she tries to pay him, he refuses, and they say goodbye at the door.
A turning point arrives when Benjie finds a eugenics textbook in the house his family rents. The boys examine it in an abandoned chicken coop, discovering anatomical illustrations and photographs of sexual activity. Benjie is horrified, while Oscy erupts with excitement and declares they will all participate in sex.
At the local movie house, the woman asks Hermie to come by Thursday morning to help move boxes. Oscy interprets this as romantic interest and arranges a double date to the movies with Miriam, a bold blonde, and Aggie, a quiet girl. During the film, Hermie attempts to feel Aggie's breast but, confused by her loose blouse, spends 11 minutes unknowingly squeezing her arm. When Oscy reveals the truth afterward, they dissolve into laughter.
Hermie's Thursday visit to the woman's house deepens his infatuation. While placing boxes in her attic from a ladder, he has elaborate fantasies, though she is merely steadying the ladder as his legs tremble. She tries to pay him; he places the dollar on the bed, then realizes the gesture's awkward connotation. She kisses him on the forehead, and he stumbles out.
Using Benjie's book, Oscy copies out a 12-step guide to performing the sexual act and announces a marshmallow roast on the beach with Miriam and Aggie, framing Aggie as Hermie's practice run. Hermie endures a comic ordeal purchasing condoms from the island druggist, claiming they are for his brother in the Rangers.
The marshmallow roast exposes Hermie's paralysis. Each time Aggie signals availability, Hermie retreats to toast another marshmallow. Meanwhile, Oscy repeatedly returns from the darkness to consult Hermie's notes and borrow condoms, reporting that he and Miriam have surpassed all 12 steps. Hermie eventually witnesses Oscy and Miriam having sex and walks away, devastated.
The next morning, Hermie recognizes that his inability to act stems from his fixation on the woman. He spots her on a dune writing a V-mail letter, a form of wartime military airmail. They chat, and he asks to visit that evening. He finally learns her name: Dorothy.
Hermie spends the day building resolve. He dresses in his finest clothes and pockets his last condom. On the way to Dorothy's house, Oscy intercepts him, wanting to recount his experience with Miriam, but Hermie refuses to listen and they quarrel bitterly before parting in anger. Walking alone, Hermie examines the condom, recognizes the absurdity of arriving prepared for a supposedly spontaneous act, and buries it in the sand.
Dorothy's house is dimly lit and quiet. Inside, Hermie finds a half-empty bottle of scotch, a full ashtray, and a phonograph needle scratching at the end of a record. Behind the bottle lies a crumpled telegram: "We regret to inform you that your husband..." Dorothy appears in a pink robe, her eyes red. She plays a record she shared with her husband and sways to it, tidying the room to hold herself together. Hermie says, "I'm sorry." She touches his face, catching his tears, and places her head against his shoulder. They dance. Dorothy leads him to the bedroom, where their lovemaking is rendered through fragmented, lyrical images: the bedspread turning down, the pink robe floating to a chair, saddle shoes beside pink scuffs. Hermie's inner voice protests, but he loves her and cannot stop.
Afterward, Hermie is consumed by guilt. Dorothy rises, stops the phonograph, and quietly tells him to go home. He dresses and descends the steps to the beach.
He sits on the beach all night. At dawn, Oscy finds him and sits beside him playing his harmonica, offering to listen. Hermie walks away in silence and climbs to Dorothy's house. It is shuttered and empty. An envelope tacked to the door reads "Hermie." Her letter tells him she must go home and will not explain what happened because in time he will find the right way to remember it. She wishes him only good things.
The narrative returns to 1970. The adult Hermie turns from the house, pondering a truth it took years to accept: "Life is made up of small comings and goings, and for everything a man takes with him, there is something he must leave behind" (202). He reflects on those now gone: his mother, his father, and Oscy, killed in Korea on Hermie's 24th birthday. Oscy's Silver Star, a military decoration for valor, was hung on his brother, the dentist. Hermie hears the boys' voices one last time and briefly sees them running on the beach before they vanish into the fog. As for the rest of that summer, Benjie broke his watch, Oscy gave up the harmonica, and "in a very special way, Hermie was lost forever" (203). At his car, a sea gull has left droppings on the windshield. Someone remembered him after all. He cries all the way home.