The novel follows Wyatt Fletcher, a taciturn thirty-eight-year-old who lives in a self-sustaining cabin on Fletcher Mountain, a secluded mountaintop property he purchased in rural Colorado outside the tiny community of Jamestown. Two of his three brothers, Calder and Luke, built cabins on the property alongside him. Together they run their late father Steven's house-renovation business. Two years after Steven's death from a heart attack, Wyatt wants to become a father but has no interest in marriage. He has spent months interviewing surrogates through a Denver agency without finding a match.
The story opens when Wyatt discovers that Calder has posted a crude surrogate ad at the local bar and on Craigslist, directing responses to their eighteen-year-old niece, Everly, the daughter of their eldest brother, Max. Everly asks Wyatt for one week to interview candidates. He reluctantly agrees, planning to cancel if his next agency appointment produces a match. When the agency director tells him he is "unmatchable," his future rests entirely on Everly's efforts. Everly, however, harbors a secret agenda: She wants to find not just a surrogate but a romantic match for Wyatt. Her interviews with six respondents all fail. Desperate, she drives to the agency building, where the glass door swings open into her face. The woman behind it is Trista Matthews, a twenty-eight-year-old rejected by the same agency for exceeding their weight limit. Everly evaluates Trista and asks if she would consider having her uncle's baby. Trista agrees to learn more.
Everly arranges a meeting at the Jamestown Mercantile, the town's bar and general store. Trista explains she wants to open a wildlife rescue facility and needs startup funds. She proposes traditional surrogacy, using her own egg and at-home insemination rather than in vitro fertilization, citing the lower cost. Wyatt, attracted to her blunt honesty, agrees to negotiate terms. They finalize a legal contract: Trista will receive seventy-five thousand dollars total, with free housing in the barn apartment on Wyatt's property. After medical testing, Trista moves onto Fletcher Mountain with her potbellied pig, Reginald. She is struck by the converted hayloft with vaulted ceilings and mountain views. Wyatt has forbidden his brothers from interacting with her, citing a painful history involving a woman named Robyn who nearly destroyed their bond.
Their first insemination attempts are nerve-wracking and comically improvised. They repeat the process over a week, each session intensifying the unspoken tension between them. When pregnancy tests come back negative, Trista suggests they try having actual sex. Wyatt responds with unexpected eagerness, but they table the discussion. The following month, the original method works. Trista attaches a positive test to the halter of Millie, Wyatt's Nigerian dwarf goat, as a surprise reveal. Wyatt reads the result and is overcome with emotion, but Trista congratulates him in a notably professional tone. He registers the distance: The baby is his, not theirs.
Trista develops severe morning sickness, hiding her condition until Wyatt finds her hunched over the toilet. He begins leaving daily breakfast deliveries and arranging errands on her behalf. Trista resists, insisting she has cared for herself since age sixteen. She reveals her parents abandoned her when she was fourteen, and her older sister, Vada, left two years later, leaving Trista to finish high school alone. Wyatt proposes they become friends, and she tentatively agrees, though she calls his escalating attentions "dad bombing." At the seven-week ultrasound, Wyatt's mother, Johanna, arrives uninvited with flowers. Trista, moved by a mother who would attend such an event, invites Johanna in.
The dynamic shifts when Trista's veterinarian friend Avery delivers a rescued miniature horse to the property. Wyatt discovers Avery is a man, not a woman as he had assumed, and his jealousy erupts. Trista scolds him, and their argument ends with a lingering kiss on his cheek that leaves both shaken. At Everly's graduation party at Max's Boulder home, Trista bonds with Max and with Cozy, a close family friend. Max offers charitable support for Trista's future rescue facility. Wyatt bristles, feeling Trista accepts help from everyone except him. After a tense drive home, their argument in the barn gives way to a passionate sexual encounter. They agree to what Trista calls a "sexuationship," a purely physical arrangement with ground rules: a sundown schedule, secrecy from the brothers, and no falling in love.
Over the following weeks, their relationship deepens while they maintain the pretense of professionalism. Trista steadily populates the property with rescued animals. The brothers defend her honor in a bar fight against locals spreading cruel rumors, and their loyalty moves Trista to tears. When coyotes destroy her chicken coop one night, Wyatt rebuilds and reinforces it by dawn. Meanwhile, Trista learns the full story of Robyn from Luke: Robyn became pregnant, told Wyatt the baby was his, and led him to consider marriage before a paternity test revealed the baby belonged to her hidden husband. Wyatt was devastated because he had always wanted to be a father.
When Wyatt suggests Trista stay on the mountain past her lease, she interprets the offer as charity and retreats. She accuses him of being drawn to her pregnancy rather than to her as a person and demands a return to business only. Trista stops eating and faints at the pasture fence. At the hospital, doctors confirm the baby is healthy and attribute Trista's collapse to low blood sugar. Wyatt crawls into her hospital bed and holds her while she cries. She insists she is not built for family life. Wyatt admits to his brothers he is in love with Trista, and Luke urges him to fight for her. Separately, Vada calls Trista and delivers a blunt assessment: Choosing loneliness over rejection is self-destruction, not protection. Alone in the barn afterward, Trista feels the baby kick for the first time.
Everly organizes a combined gender reveal and baby shower before leaving for college in Ireland. Wyatt's family presents Trista with personal gifts, pointedly for her and not the baby, acknowledging her as someone they value. Overwhelmed, Trista flees to the barn. Wyatt follows, and she tells him she is tired of pretending. She presses his hand to her belly so he can feel the baby kick, then confesses she cannot give the baby up, accidentally revealing the baby is a girl. Wyatt tells her he does not want to amend the contract; he wants to tear it up entirely. He confesses he is in love with her. Trista says she loves him too. At the airport, as the family sees Everly off, Everly reveals she engineered the match all along.
In the final chapters, Trista moves into Wyatt's cabin. They name the baby Stevie Everly Fletcher, honoring Wyatt's late father and his niece. Stevie is born healthy past her due date. On the family's first morning home, Wyatt finds Trista swaying with Stevie at the windows, watching the mountain sunrise. He kneels beside her, places a ring box on the baby's swaddled belly, and proposes. Trista says yes. Two months later, Trista is fully integrated into the Fletcher family, planning her wildlife rescue center with Max's support and calling Johanna "Jo." Fletcher Mountain now houses at least 16 animals, and Trista reflects that she has found the family she never had.