In the 1980s Virginia, a young girl named Maren Yearly inadvertently bites off a portion of a girl’s finger during a sleepover, triggering a series of dark events. Following this unsettling incident, she and her father, Frank, pack up and move to Maryland. However, shortly after Maren turns eighteen, Frank abandons her with merely a stash of cash, her birth certificate, and a haunting tape. In this recording, he recounts the disturbing tale of Maren's first cannibalistic act, during which she killed her babysitter at just three years old. Though Frank tried to shield her from the consequences of her actions over the years, he was constantly tormented by her apparent lack of remorse. He ends his recording with a desperate hope that she might one day control her unsettling urges.
Determined to uncover her past, Maren travels to Minnesota, the birthplace of her mother, Janelle. With no memories of her, she takes a bus to Columbus, Ohio, where she crosses paths with Sully, a peculiar man who shares her disturbing cravings. Following Sully, she unwittingly becomes a witness to his grotesque act of consuming a dying woman’s body, prompting her to flee from his side.
While trying to shoplift in Indiana, Maren encounters Lee, another "eater," right after he dispatches a man who menaced a store customer. As fate would have it, Lee offers her a ride in the stolen truck, and together they embark on a haunting cross-country journey where they gradually bond over their shared fate. During one of their stops in Lee's hometown in Kentucky, Maren starts noticing his reluctance to explain his father's absence, while his younger sister Kayla remains blissfully unaware of her brother’s dismal truth and scolds him for his frequent escapades.
Their journey takes a dark twist when they meet two other eaters, Jake and Brad. Maren is appalled to discover that Brad doesn’t share their hunger but instead chooses to engage in cannibalism willingly. The couple drives away in the dead of night to escape the horrifying situation.
Their road trip turns even more sinister when, during a visit to a carnival, Lee, overtaken by his primal instincts, kills a male booth worker for them to feast on. The moment Maren realizes the man had a family, overwhelming guilt washes over her. Desperate for answers, Maren locates her grandmother Barbara, who had no idea of her existence. Barbara reveals that Janelle was adopted and is now residing in a psychiatric hospital.
When Maren finally meets Janelle, she is shocked to find that her mother has resorted to self-cannibalism and has written her a poignant letter expressing the belief that Maren might be better off dead. A confrontation ensues, resulting in Janelle attacking Maren before being subdued by a nurse. Overcome with despair, Maren sneaks away while Lee is asleep, only to be confronted by Sully, who has been stalking her. She pushes him away, prompting his furious departure.
Eventually, guilt pulls Maren back to Kentucky, where she learns of Lee’s troubled past from Kayla. Lee was wrongfully implicated in their father's disappearance, which had occurred after a cruel incident at home. Fortunately, Maren and Lee find their way back to each other, reigniting their connection as they head westward. As trust deepens, Lee uncovers his own dark truth about his father being an eater and the horrific culmination of their relationship in a violent clash.
Months roll by, and the couple finds their happiness in Ann Arbor, Michigan, where Maren leads a semblance of a normal life working at a university bookstore. However, tranquility shatters when they discover Sully has intruded into their apartment, brandishing a knife and threatening their lives. In a desperate struggle, they manage to kill him, but not without a heavy price—Lee suffers fatal injuries in the process. Amidst the chaos, Maren uncovers disturbing evidence indicating that Sully may have claimed Kayla as his victim. In his dying moments, Lee makes a haunting request for Maren to eat him, which she ultimately fulfills as they both confront their dark destinies "bones and all."
