Deputy Keith Clayton, a sheriff's deputy in Hampton County, North Carolina, is secretly photographing nude college students at a remote creek when he spots a stranger walking along a nearby logging road. The stranger, Logan Thibault, is a former Marine traveling on foot from Colorado with his German shepherd, Zeus. Thibault witnesses Clayton's behavior and retrieves the hidden camera while Clayton is distracted. He also flattens both of Clayton's rear tires before hitching a ride toward Hampton. When Clayton discovers the camera and its incriminating disk are gone, he vows to track Thibault down.
Thibault's journey began with a photograph. During his deployment to Kuwait before the 2003 invasion of Iraq, he found a laminated snapshot half-buried in the dirt showing a blonde woman in a T-shirt reading "LUCKY LADY," standing before a banner reading "HAMPTON FAIRGROUNDS" with a German shepherd at her side. On the back is written, "Keep Safe! E." No one claimed the photo, and Thibault pocketed it before the invasion. That night, his best friend, Victor, a fellow Marine who believed in omens, talked him into a poker game. Thibault won back everything he had previously lost, and Victor declared the photograph a lucky charm. He also warned Thibault never to lose it, claiming the charm would reverse if he did.
Over three tours in Iraq, Thibault survived a rocket-propelled grenade (RPG) strike that killed two members of his fire team, an ambush in Fallujah that killed two more squadmates, and 11 improvised explosive device (IED) and car bomb explosions in Ramadi. His fellow Marines began to distrust him, believing his luck came at others' expense. Only Victor treated him the same and urged Thibault to find the woman in the photograph after the war, calling it his destiny. After their discharge, Victor died in a boating accident. Devastated, Thibault spiraled into grief. Prompted by Victor's words, he packed a backpack and began walking east to find the woman in the photograph.
In Hampton, Thibault confirms the fairgrounds match the photo. At a pool hall, he shows the picture to a group of young men who identify the woman as Beth Green, a second-grade teacher. Beth lives at Sunshine Kennels, a dog obedience training business run by her grandmother, Nana, who had a stroke earlier that summer. Beth is raising her 10-year-old son, Ben, with Nana's help. Beth's parents died in a car accident when she was three, and Nana and her late husband raised Beth and her younger brother, Drake. Drake, also a Marine, was killed by friendly fire during the first week of the Iraq invasion, a loss Beth has never fully reconciled. Beth married Keith Clayton when she was young and pregnant but divorced him within nine months. Keith comes from the most powerful family in the county: His grandfather, Gramps, owns most of the commercial property in town, and his father is the county sheriff. Keith has joint custody of Ben, who dreads his biweekly visits because his father is perpetually disappointed that Ben prefers reading, chess, and the violin to athletics.
Thibault walks to the kennel and applies for a job. Beth is suspicious, but Nana hires him on the spot, trusting her instincts. Thibault proves to be an exceptional employee, and he bonds with Ben over Zeus, chess, and the violin. When Nana leaves for a week to visit her sister, Thibault takes on extra responsibilities, and he and Beth begin spending evenings together, walking by the creek and talking on the porch.
Meanwhile, Clayton discovers Thibault is in Hampton and working at the kennel. For years, Clayton has been sabotaging Beth's romantic relationships, using his authority as a deputy and his family's influence to intimidate the men she dates into disappearing. Furious to find Thibault in Beth's life, Clayton breaks into Thibault's house searching for the camera disk, but Thibault destroyed it shortly after arriving in Hampton. Thibault notices signs of the intrusion and deduces Clayton's involvement.
Beth and Thibault's relationship deepens. On Drake's birthday, Beth shares the story of the photograph she gave Drake before he deployed and her guilt over not sending a replacement when he lost it in Iraq. Thibault, shaken by the realization that the photo he has carried for five years is the very one Drake lost, listens without revealing the truth. On their first official date in Wilmington, they dance, share stories, and confess their love. Thibault offers a carefully edited version of his past, omitting the photograph.
Thibault tells Beth he suspects Clayton has been sabotaging her relationships. Beth investigates by visiting Adam, a man she briefly dated, whose terrified reaction confirms Clayton's interference. She confronts Clayton, who denies everything and pivots to warning Beth that Thibault may be hiding a dangerous past. Despite knowing Clayton is a liar, Beth is unsettled by how little she knows about Thibault's background. Thibault then confronts Clayton directly, bluffing that he has video evidence of the break-in and the original disk. He demands Clayton stay out of Beth's life and never take his anger out on Ben. Clayton backs down, but Thibault knows the bluff will not hold indefinitely.
When the church pianist breaks her wrist, Nana volunteers Thibault to fill in. His performance earns enthusiastic applause. After the service, Tony, a local hanger-on who associates with deputies, tells Clayton that the stranger who showed Beth's photograph at the pool hall months earlier is Thibault. Clayton realizes Thibault walked across the country to find Beth and decides this information is his weapon.
During a visit to Ben's tree house, which weeks of storms have severely weakened, Thibault feels a compulsion he cannot explain and gives Ben the laminated photograph, telling the boy it is a lucky charm. For the first time in five years, Thibault is without the photo.
Clayton visits Beth at her school, first offering a partial apology for interfering in her past relationships, then revealing that Thibault had her photograph before arriving in Hampton and walked across the country to find her. He frames Thibault as a dangerous stalker. Beth confronts Thibault at the kennel, and he admits the truth. When he tries to explain that the photo kept him safe and that he felt he owed her a debt, Beth hears only deception. She orders him to leave, and he walks out into the storm.
After talking with Nana and learning from Ben that "his friend Victor" called the photo a lucky charm, Beth realizes there is more to the story. She drives to Thibault's house, where he has packed his backpack but cannot bring himself to go. He tells her everything: the firefights, the IEDs, Victor's unwavering belief in the charm, Victor's death, and the sense of destiny that prompted his journey. Beth recognizes the man she loves in his honesty and forgives him.
Clayton, spying on Thibault's house, sees Beth's car and is enraged. As a catastrophic storm floods Hampton County, he storms into Beth's house and threatens to seek full custody of Ben unless she ends things with Thibault and agrees to date Clayton, citing Thibault's stalking as evidence. Ben, overhearing from the stairs, shouts that he will never live with his father and runs into the storm toward his tree house. Beth and Clayton race after him through the flooded woods.
They reach the creek to find Ben clinging to the fraying rope bridge beneath the collapsing tree house. Clayton climbs onto the bridge, but the planks break under his weight and he crashes into the torrent. Thibault, who noticed Clayton's tire tracks and sprinted to the property, dives into the flooded creek with Zeus close behind. The remaining pilings collapse, sweeping Ben into the water. Zeus fights through the current, reaches the boy, and Ben grabs the dog's tail. Zeus pulls him to shore. Beth, hobbling on a broken foot, reaches them as they stagger from the water. Clayton does not survive. Thibault is later found and recovers.
Two months later, Beth reflects on the aftermath. She chooses to remember Clayton with gratitude for his attempt to save their son. Nana has continued to improve, and Ben carries the photograph everywhere, though he still has nightmares about the flood. Logan is at home, building a new tree house in the backyard. Beth visits both Drake's and Keith's graves, leaving flowers. When she pulls into the driveway, Logan walks down the steps and opens his arms.