The Shippers

JoJo Burton, a 26-year-old mathematician and serial boyfriend-dumper, stands at the altar in her future mother-in-law's itchy, outdated gown, its zipper caught in her hair. She is about to marry Pearce Richmond, her college boyfriend, whose emotional unavailability kept her hooked for seven years, preventing her usual pattern of losing interest once a man becomes attainable. An ultimatum led to a four-year engagement that became a wedding only after Pearce's parents pressured him about grandchildren. Now that she finally has him, she does not want him.

Cooper Watts, JoJo's childhood best friend and across-the-street neighbor, bursts in looking radically different: muscular, bearded, carrying a rucksack. He moved to London four years earlier without explanation, ghosted JoJo entirely, and RSVPed no with a note calling the wedding a boycott. JoJo feels a spark when he tells her she looks beautiful. Cooper suggests she could fake a faint. JoJo's father, an absentee workaholic ex-marine, has missed his flight, so Grandma Dodie, her 78-year-old maternal grandmother, walks her down the aisle. During the sermon, JoJo catches Cooper's eye and lets her knees buckle.

Cooper carries JoJo to the bridal room, where she opens her eyes to find him, not Pearce, holding her. When she calls off the wedding, Pearce's mother storms in and charges at her. Cooper hoists JoJo over his shoulder, carries her to a rented Jeep, and drives to Galveston. He reveals he flew from London specifically to tell her something but refuses to say what. He departs at dawn.

Six weeks later, JoJo's family prepares for her older sister Ashley Burton's cruise ship wedding to Brody. Ashley proposes that JoJo imprinted not on her neglectful father but on her first kiss: Finn Turner, a boy from their childhood street who kissed her during a blindfolded truth-or-dare game when she was 10. That kiss became her emotional touchstone, especially because it coincided with the day her father forgot to pick her up from school, leaving her to walk home in the rain and develop pneumonia. Finn, now a newly divorced lawyer, has RSVPed yes. Ashley launches "Operation Conquest" to engineer proximity between JoJo and Finn.

The night before departure, JoJo overhears her mother tell her father she wants a divorce after he accepted a job transfer and put their house up for sale without consulting her. JoJo keeps this from her siblings.

On embarkation day, Cooper appears clean-shaven and dressed in a gabardine vest. JoJo recruits him as her wingman for Operation Conquest, dismissing him as a romantic prospect by citing a kissing booth incident from senior year when she kissed Cooper and he vomited all over the booth. Cooper calls it the worst idea she has ever had. Aboard the ship, Cousin Harmony commandeers their cabin for hookups, so JoJo moves into Cooper's stateroom, sharing a bed divided by a pillow wall. JoJo reveals her fear of singing, rooted in a cruel first-grade teacher, and confesses she only ever sang with Cooper. Ashley expects JoJo to serenade her at the reception. Cooper offers to sing a duet: "Tonight, You Belong to Me."

Operation Conquest stumbles: Finn does not recognize JoJo despite having lived across the street. At a mini-golf tournament, Cooper stays by her side, deliberately matching her terrible scores and hyping her to the other guests. Inspired by Cousin Harmony's lecture on biosemiotics, or how living things signal to each other, JoJo asks Cooper to give her a hickey. He refuses, but after JoJo's raw outpouring about his four-year abandonment, he relents. JoJo considers the experience the best kiss of her adult life, though she insists it was not a kiss. The hickey fails as signaling, but they pivot to fake flirting, and Finn asks JoJo on a kayaking date.

JoJo offers to help save her parents' marriage. Her father admits he worked obsessively because growing up poor convinced him that providing financially was his duty. That night, as Cooper applies aloe to JoJo's sunburn, he reveals his traumatic past: His controlling father kidnapped him during his parents' divorce and locked him in a closet for four days. Cooper escaped through a second-story window. His mother changed their names and moved to JoJo's street. This trauma is the source of his cleithrophobia, a fear of being trapped, and he has never told anyone.

Cooper challenges Operation Conquest, calling Finn wrong for JoJo. She insists she must confront her first kiss. At Ashley's slow-dance contest, Finn abandons JoJo mid-song for a work call. Cooper rescues her, and they dance to a standing ovation. Finn claims the prize and leads JoJo to the moonlit deck for a kiss, but she feels nothing.

Racing back to Cooper, JoJo finds a dirty sock on their cabin doorknob and assumes he is inside with Mia Macall, a bridesmaid. Unable to find another room, she sleeps alone in Finn's cabin. The next morning, Cooper sees her leaving Finn's room and assumes the worst. On the balcony, he blindfolds her with his tie and reveals that the playground kiss was not from Finn, who had ditched her, but from Cooper himself, who at 10 could not bear to disappoint his best friend. He presses her childhood flower barrette into her hand and leaves the ship.

JoJo's father intercepts her: Ashley's dress needs altering on the island of Bishop's Cay. After delivering it, JoJo searches an abandoned lighthouse hoping to find Cooper, but a man she confronted earlier for harassing a woman follows her and locks her inside. Her father tracks her phone and rescues her, racing back to the ship with minutes to spare. Cooper does not board. Her father then reveals that on the day she walked home in the rain, he was at the school, parked at the wrong entrance and searching for hours.

JoJo learns from Mia that Mia spent the sock night with another passenger, not Cooper. At Ashley's reception, JoJo freezes at the microphone. Cooper walks in, having flown from a Bahamian hospital: He arrived at the lighthouse to rescue JoJo, was slashed by her attacker with a broken bottle, and lost consciousness. They perform their duet to a standing ovation.

In a darkened stairwell during a power outage, Cooper confesses the sock: He placed it in jealous rage after watching Finn kiss JoJo, then removed it within five minutes. JoJo kisses him to calm his claustrophobic panic, and he tells her he is in love with her. Later, on the moonlit deck, he explains that he left for London because he could not watch her marry Pearce, having loved her his entire life. He reveals he has been running his own Operation Conquest, conspiring with JoJo's mother and Ashley.

JoJo kisses Cooper as the ship's power returns, flooding light through the ballroom doors and illuminating them for the cheering guests. Cooper proposes with a conch-shell ring from Bishop's Cay. JoJo insists she is cursed, but Cooper argues he is her loophole: the person she imprinted on, the one she has loved all along. She accepts.

In the epilogue, JoJo's parents reconcile. JoJo discovers that nominal aphasia, a condition affecting name recall, explains her father's forgetfulness, reframing perceived indifference as neurodivergence. She reflects that love is like math: complex, hidden, and beautiful, and compares her bond with Cooper to a Möbius strip, an infinite loop, concluding they had been endless all along.