Mavis Gary, a divorced, thirty-something ghostwriter of a once-popular young adult book series, finds herself in a state of stagnation, both professionally and personally. Living in a Minneapolis high-rise, Mavis leads a life filled with empty alcohol bottles, a neglected dog, and fleeting romantic encounters. Her days are spent under the pressures of looming deadlines and creative decline, as her publisher announces the imminent end of her book series. Craving change and a spark of nostalgia, Mavis is spurred into action by an email announcing the birth of her high school boyfriend's first child.

Compelled by an idealized remembrance of her teenage years, Mavis returns to her small, rural hometown of Mercury, Minnesota, with a mission: to rekindle a romance with her high school sweetheart, Buddy Slade, in spite of his new status as a happily married father. Armed with a sharp tongue and a misguided sense of confidence, Mavis bulldozes into town, reconnecting with old acquaintances, including her former classmate, Matt Freehauf, who serves as an unexpected voice of reason. Matt, a victim of a high school hate crime that left him with permanent injuries, becomes a reluctant confidant and a counterpoint to Mavis's delusions of reclaiming a lost love from a bygone era. As Mavis pursues her fantasy, her presence shakes the small town and the lives within it, leading to a series of comically raw and poignant encounters.