In 2019, Trevor Benson, a thirty-seven-year-old psychiatrist, attends a wedding at an alpine-style church in the American South. He has known the bride for more than five years, though he is unsure she considers them friends. Their bond is rooted in events that began years earlier, involving two very different women, one of whom was really just a girl at the time. He invites the reader to travel back to 2014.
Trevor is thirty-two, a convalescing physician and disabled veteran, when he moves into the run-down house his late grandfather Carl built after World War II outside New Bern, North Carolina. The property sits on six acres along Brices Creek and includes about twenty beehives, a honey shed, and a barn. Three years earlier, a rocket blast at Kandahar Airfield in Afghanistan blinded Trevor's right eye, blew off two fingers and his left ear, scarred his face, and caused spinal injuries. The Navy discharged him on disability. He spiraled into post-traumatic stress disorder (PTSD) before a psychiatrist named Dr. Eric Bowen helped him manage his condition through behavioral therapies. He has been accepted into a psychiatric residency at Johns Hopkins, beginning in July.
Shortly after moving in, Trevor notices a guarded, pale teenager with bruises on her arms who walks past the house from a nearby trailer park. She introduces herself as Callie, tells him the mothballs he is scattering will not repel snakes, and mentions that Carl used to give her honey. Carl's death is what brought Trevor here, and its circumstances haunt him. Carl suffered a stroke in Easley, South Carolina, a town Trevor had never heard him mention. In their final conversation, Carl uttered confusing phrases, including what Trevor heard as "go to hell," along with fragmented words about someone collapsing, being sick like his late wife Rose, and finding family. Carl died less than two hours later. Trevor wrote the words down and kept them in his wallet, determined to understand his grandfather's message.
One evening, Deputy Sheriff Natalie Masterson arrives to check on the property, explaining that a hunter reported candlelight in the windows and she found signs of an unusually tidy squatter. Trevor is immediately drawn to her. They meet again at the Saturday farmers' market, where Natalie is uncomfortable being seen with him, but she later finds Trevor at a nearby park and apologizes. She reveals she grew up in La Grange, North Carolina, and followed a boyfriend named Mark to New Bern but deflects further questions about him. Their relationship deepens: Trevor shows her the beehives, they share personal histories over dinner in Beaufort, and he takes her boating on the creek. Trevor reveals his parents died in a plane crash before his college graduation, leaving him an orphan at twenty-two. After a candlelit dinner on the back porch, Natalie admits she has been seeing someone else but confesses she has fallen for Trevor. They share their first kiss, but she abruptly pulls away, saying she cannot go through with it. Days later, despondent, she asks Trevor to promise something important; he agrees, and she tells him they must stop seeing each other and never contact her again.
Devastated, Trevor turns to investigating Carl's journey. At the Trading Post, a local store where Carl was a regular, an old-timer named Jim mentions that Carl was going to visit "Helen" and references "the girl inside," identified as Callie. When Trevor asks Callie about Helen, she panics and storms off. He traces Carl's movements to a motel near Easley where Carl was found slumped in his truck before his stroke. Meanwhile, Trevor deduces that Callie was the squatter in Carl's house: A jar of peanut butter left behind, though Carl was allergic to peanuts, and Callie's use of Rose's social security number at the hospital confirm his suspicion.
During a severe storm, Callie collapses from a stepladder at the Trading Post. Trevor identifies a serious head wound with blood from her ear, suggesting a subdural hematoma (bleeding around the brain), along with compound fractures. With roads flooded, he organizes an improvised transport to the hospital. Her oncologist, Dr. Mollie Nobles, explains that Callie has advanced aplastic anemia, a condition in which her body fails to produce enough new blood cells. She needs a bone marrow transplant, but the national registry has no adequate matches. Family members are the most likely donors, yet Callie refuses to reveal her identity, insisting her family hates her.
Trevor searches Callie's trailer and finds University of Georgia memorabilia with birthdays marked in red. Natalie, arriving on a sheriff's call, helps him open a box of Carl's personal effects sent by a towing company's attorney. Inside are two highway maps with routes highlighted from New Bern through Easley into Georgia, ending at a town called Helen. Trevor realizes Carl was traveling not to a woman named Helen but to the town of Helen, Georgia, to find Callie's family. Natalie then reveals why she has been so conflicted: She drives Trevor to a long-term care facility where her husband Mark lies in a persistent vegetative state, the result of bacterial meningitis contracted during their anniversary trip to Charleston. Mark's mother holds medical power of attorney and refuses to end life support. Natalie tells Trevor she cannot divorce a man incapable of contesting it.
The next morning, Trevor reexamines Carl's deathbed words and reinterprets them: "Go to hell" becomes "Go to Helen," and "help care" becomes "help Karen." Carl had been trying to tell Trevor about a sick runaway named Karen whose family lived in Helen. Police Chief Harvey Robertson searches the Georgia Bureau of Investigation's database and finds her: Karen Anne-Marie Johnson, age sixteen, who ran away after her four-year-old brother Roger choked to death while she was supposed to be watching him. Back at the hospital, Callie tells Trevor the full story: her overwhelming guilt, overhearing her parents blame her, and running away by bus until she reached New Bern, where Carl found her sleeping in his barn and took her in.
Trevor persuades Callie to call her parents. Her parents, Curtis and Louise, along with her twin sisters Tammy and Heather, drive through the night. The reunion is emotional. All four family members are tested for bone marrow compatibility, and Dr. Nobles reports that Heather is a perfect match on all six human leukocyte antigen (HLA) markers, the tissue-type indicators used to determine donor compatibility. The transplant is scheduled.
Natalie and Trevor share a bittersweet goodbye outside the hospital, telling each other "I love you" before parting. Trevor prepares the house for vacancy and leaves jars of honey on Natalie's doorstep. In Baltimore, he discovers a letter she tucked into his moving boxes. She writes that loving him was one of the most exalted experiences of her life but begs him never to contact her, because if he asks her to come, she will not be able to resist.
The epilogue returns to the 2019 wedding. Trevor has completed his residency. Callie's transplant was successful; she graduated high school, became a dental hygienist, and is marrying Jeff McCorkle at twenty-one in Helen, Georgia. Trevor asked Callie to invite Natalie. At the reception, he finds Natalie by a magnolia tree. She reveals that Mark died of a pulmonary embolism (a blood clot in the lung) ten months earlier. She no longer wears her wedding ring and has left the sheriff's department to open a flower shop in New Bern. Trevor mentions job offers in the area, and she notes the region's shortage of psychiatrists. She accepts his invitation to harvest honey at his grandfather's house, requesting dinner on the back porch afterward. She kisses him, and they enter the reception tent together.