The novel opens with a fictionalized version of its author describing how he discovered the story. In late spring 2016, he visits Kindred Spirit, a communal mailbox on Bird Island near Sunset Beach, North Carolina, where anyone can leave or read anonymous letters. He finds a thick manila envelope containing pages of narrative and drawings of a couple in love. When the envelope disappears a week later, he tracks down one of its subjects, an older man building a ramp at a beach house, who agrees to let the story become a novel on the condition that real names not be used.
The story begins on September 9, 1990. Tru Walls, a 42-year-old safari guide in Hwange National Park, Zimbabwe, sets out for America to meet his biological father for the first time. Tru comes from one of Zimbabwe's wealthiest families; his grandfather, known as the Colonel, built a farming empire near Harare through ruthless means. When Tru was 11, the family compound burned in a suspected arson fire. Tru escaped, but his mother, Evelyn, died. Both the Colonel and Tru's stepfather, Rodney, withdrew emotionally, and Tru was raised largely by farm workers. He began drawing to cope with grief. Now he has received a letter, a plane ticket, and a photograph of Evelyn with an American man. He arrives at a beach house at Sunset Beach and learns his father will not arrive for four days.
Next door, Hope Anderson, a 36-year-old trauma nurse from Raleigh, has arrived at her family's cottage for the week before her friend Ellen's wedding. Hope faces her father's terminal diagnosis of ALS (amyotrophic lateral sclerosis, a progressive neuromuscular disease), the impending sale of the cottage, and a troubled relationship with Josh, her boyfriend of six years. Josh, an orthopedic surgeon, broke up with her after an argument and went to Las Vegas instead of accompanying her to the wedding. At 36, Hope fears her dream of marriage and motherhood is slipping away.
Tru and Hope meet Wednesday morning when Hope's Scottish terrier, Scottie, is apparently grazed by a car. Tru finds the injured dog and carries him to the beach. Hope invites him for coffee, and they talk easily, each feeling an immediate attraction. That evening, both go independently to Clancy's, a local restaurant, and share dinner. Walking the beach afterward, Tru reveals the story of his mother's death. Over wine on Hope's deck, she tells him about her father's illness.
Over the next two days, their bond intensifies. On Thursday, they walk to Kindred Spirit at low tide and read letters at the mailbox. Hope confides her longing for children. On the walk back, a storm overtakes them, and Tru leans in to kiss Hope, but she stops him with a gentle hand on his chest. They hold hands the rest of the way home. That evening, after Josh calls from Las Vegas and Hope hangs up on him, she and Tru kiss passionately, and she leads him to the bedroom. On Friday morning, they exchange declarations of love. Tru sketches Hope's portrait and begins a drawing of the two of them in profile. Hope leaves for Ellen's rehearsal dinner.
On Saturday, Tru's biological father, Harry Beckham, arrives. Harry is in his midseventies, frail and terminally ill with lung cancer. He recounts falling in love with Evelyn while working at a mine in Rhodesia (the former colonial name for Zimbabwe) and hints that the Colonel was abusive toward her. When the Colonel discovered the relationship, his men kidnapped, beat, and expelled Harry from the country. Harry fled, never seeing Evelyn again and unaware she was pregnant. He gives Tru photographs and a stack of Evelyn's original drawings.
That same evening, Hope attends Ellen's wedding, where Josh appears unexpectedly, apologizes, and proposes marriage. On Sunday morning, Hope tells Tru she loves him but cannot leave her dying father, and the one thing Tru cannot give her, biological children (he is sterile due to a childhood illness), is something she cannot live without. Though she has not answered Josh, Tru understands her decision. He begs her to come to Zimbabwe, but Hope refuses through tears. Before she leaves, Tru secretly places his drawings and a love letter into her glove compartment, writing that she is forgiven and that if she ever needs him, he will come. They embrace one last time, and Hope drives away.
Back in Raleigh, Hope discovers the drawings and letter and is overwhelmed. Eight weeks later, she accepts Josh's proposal and marries quickly, already suspecting she is pregnant with their first child, Jacob.
Part II opens in October 2014. Hope is 60, retired, and alone, having divorced Josh eight years earlier after his affairs. She has two grown children, Jacob and Rachel. Her father died of ALS; her mother died four years later, never recovering from grief. Her unspoken love for Tru persisted throughout her marriage, and she kept his drawings, letter, and Ellen's wedding invitation in a carved wooden box. After her divorce, she spent years searching for Tru across southern Africa but failed. In one of her father's last lucid periods, she told him about Tru; her dying father, moving his hand for the first time in weeks, communicated a single question: Was she sure it was too late?
The previous year, Hope wrote a letter to Kindred Spirit asking to see Tru one last time, specifying October 16, 2014. On that day, she makes the arduous walk to Bird Island and finds, among the mailbox's letters, one on yellow legal paper addressed to "Hope" in Tru's handwriting. In it, he explains that he flew to North Carolina and visited the mailbox daily for weeks. He writes that she has always been forgiven. Hope looks up and sees Tru standing before her.
They embrace and catch up on 24 years. Tru recounts leaving Hwange after his son Andrew went to university, moving to Botswana, and losing the family farm when the Zimbabwean government seized it. His stepfather Rodney died by suicide a year later. In 2004, a catastrophic car accident left Tru clinically dead before he was revived, and he spent nearly three years in rehabilitation, relearning to speak and walk. He reveals that in 2007, he almost flew to find Hope but turned back at the airport, paralyzed by fear. Hope tells him she was searching for him at that same time.
By the fire, Hope reveals her devastating secret: She has ALS, diagnosed the previous July. Tru, drawing on his experience of dying and returning, insists she is living, not dying. He tells her he will move to North Carolina, marry her, and love her regardless of how long they have. They make love with tenderness, and Hope whispers that she would like to marry him.
In the epilogue, the fictionalized author visits Tru's friend Romy in Zimbabwe. Romy recalls Tru, devastated on one September anniversary, saying that goodbye to Hope was the hardest thing he ever did. After Tru's accident, Romy asked whether Tru saw God when he died. Tru replied: "No...I saw Hope" (317). The author returns to the beach and sees the couple: Hope sits in a wheelchair, and Tru stands beside her, his hand on her shoulder. Tru waves in farewell, and the author waves back, understanding it is their time at last.