The novel alternates between two timelines: the present, in which a young mother pushes away the man she loves, and flashbacks revealing how they fell for each other in the year following her boyfriend's death.
In the present-day chapters, set in early July, Payton Baylor is a single mother living in Oceanside, California, in a beach house she shares with her older brother, Parker. Her infant son, Deaton, is named after his late father, Deaton Vermont, Payton's high school boyfriend who died in a car accident the previous summer. Payton has been ignoring calls and texts from Mason Johnson, the starting quarterback at Avix University and a close friend of the group, for nearly nine weeks. When Mason arrives for a Fourth of July gathering, he is visibly hurt and desperate for answers, but Payton flees every attempt he makes to talk.
The flashback chapters trace the origins of their relationship. The previous summer, sixteen-year-old Payton runs away from her controlling, abusive mother, Ava Baylor, and shows up pregnant on Parker's doorstep. She has been estranged from her brother since their parents' divorce, as Ava has cut her off from both Parker and their father. Among Parker's tight-knit circle of friends, Mason is the first to break through her anxiety, tossing her into the ocean and spending hours teaching her about football. When a tear slips down her cheek, he brushes it away and whispers "Just a little water," a gesture that becomes a quiet ritual between them. Chase, Mason's best friend, also offers quiet support.
Payton's boyfriend, Deaton Vermont, tracks her to California. Mason, seeing Deaton grab Payton's wrist, tackles him to the sand before realizing he is her boyfriend. Alone with Deaton, Payton confesses she is pregnant but admits she is unsure whether she wants to keep the baby. Soon after, the group receives word of a car accident. Kenra, the sister of their friend Nate, survives, but Deaton is killed. At the hospital, Deaton's mother slaps Payton and screams that his death is her fault (107). Payton's own mother arrives and dismisses the loss, demanding Payton leave. The group shields Payton, and Chase carries her from the hospital and stays through the night.
In the weeks that follow, Mason becomes Payton's anchor. His mother, Vivian, comes to Oceanside and spends hours comforting Payton. Late one night, Mason takes Payton to a diner, where she tells him she is keeping the baby. He responds with unconditional support, telling her the reason is hers alone (125). Over the following months, as Mason begins his freshman year at Avix, the two grow closer through his visits and her trips to watch him play. Their bond deepens through playful teasing, emotional honesty, and his growing attachment to baby Deaton.
When Mason suffers fractured ribs and a sprained shoulder during a game, he secretly returns to Oceanside. Payton discovers him collapsed on the kitchen floor and refuses to leave. She tends to his injuries for weeks, and the two fall into a domestic rhythm. She removes his bandages, traces his bruises, and helps him shower in scenes charged with intimacy. She realizes she is attracted to him and whispers that she cannot be falling for Mason, only for him to appear in the doorway.
Their connection intensifies over the following months. Mason travels to Payton's hometown of Alrick and locates Deaton Vermont's grave at Carmichael Cemetery, a site the Vermont family deliberately withheld. Payton tries to kiss him in gratitude, but he stops her, saying he wants her first kiss to come from desire, not grief (266). During a spring break trip to Disneyland, she photographs him on a Ferris wheel, baby Deaton asleep on his chest. That evening, they dance on a hotel balcony, and Payton kisses him first, confessing she cannot stand the thought of not doing so (294).
Despite everything, Payton tells Mason she cannot commit to a relationship. She needs to protect her son from another devastating loss. She asks Mason not to wait, but when he presses, she admits she would want him to. He declares he will wait, and she promises that when she is ready, he will be the first to know. The next morning, as Noah Riley, the boyfriend of Mason's twin sister Arianna and a newly drafted NFL player, drives Payton home, she is struck by a realization: the man in her recurring dreams is no longer Deaton but Mason. His face, his voice, his hands have replaced her late boyfriend's without her noticing. Terror overtakes her. If losing Deaton nearly destroyed her, losing Mason would be her undoing. She decides to break her promise and cut him off.
Back in the present, this is the silence Mason has been enduring. He stops eating, misses classes, and runs obsessively. He is placed on academic probation, his scholarship at risk. Payton buries herself in work and her son, leaning on Chase during her worst moments, including the one-year anniversary of Deaton's death. Mason drives straight from practice, still in his cleats, just in case she needs him (102), but when he arrives and finds Chase already there at Payton's invitation, the perceived betrayal is crushing. He runs into the darkness.
The tension escalates during a group trip to Nevada, where Mason drinks heavily, publicly accuses Payton and Chase of being involved, and punches Chase. Payton tends to his swollen hand as he slurs that he is dying without her. Back at Avix, the backup quarterback Alister Howl, who has antagonized Mason all season, is revealed to have been fueled by a personal grudge: his ex-girlfriend falsely told him Mason fathered her child. Payton witnesses the fallout and tries to flee, but Chase brings her to the football house instead, telling her she cannot keep running (357).
Mason and Payton finally confront each other. He confesses his love (346-347) and pleads for any piece of her. She breaks, screaming that he is not competing with a ghost and that the absence of competition is precisely the problem (347). She loves Mason more than she ever loved Deaton, and the depth of that love makes losing him unthinkable.
Payton travels to Carmichael Cemetery and kneels before Deaton Vermont's headstone for the first time. She apologizes for not coming sooner, for falling in love with Mason, for letting Deaton's face fade from her dreams. Exhausted, she falls asleep on the grass. In a dream, Deaton appears and tells her their son deserves another father figure, and if it cannot be him, it must be Mason (369). She wakes to find Mason stepping out of Chase's truck and runs to him.
Payton tells Mason she loves him. He holds her face and asks her to understand: if she is his, baby Deaton is his too, permanently. She agrees. Chase lifts baby Deaton from the truck, and the toddler runs to Mason on wobbly legs. Using a photo of Deaton Vermont, Mason has taught baby Deaton to say "dada" when seeing his biological father's face, but the boy also turns to Mason and says the same word. Payton tells Mason that while Deaton is the biological father, Mason is the only dad their son has ever known (373).
That night, Mason and Payton are intimate for the first time. The next morning, she reveals that Avix University has offered her a two-year photography position. She is staying. When Mason asks what happens after that, she echoes his earlier words: wherever he is, they will be (391). She promises never to run again. The novel closes with the three of them together, heading home.