The novel alternates between two narrators, Patty Watts and her daughter Rose Gold, moving between present-day chapters set in late 2017 and flashback chapters spanning 2012 to 2017.
Patty Watts, a stocky, relentlessly cheerful woman in her late fifties, is released from Mordant Correctional Center in Illinois after serving five years for aggravated child abuse. She was convicted of poisoning and starving Rose Gold for eighteen years. Throughout Rose Gold's childhood, Patty used ipecac syrup, a substance that induces vomiting, to keep her daughter chronically ill. The resulting malnutrition caused Rose Gold's hair to fall out, her teeth to rot, and her body to remain dangerously underweight. Patty shaved Rose Gold's head, put her in a wheelchair, fitted her with a feeding tube, and pulled her out of school after a bullying incident, isolating her almost completely. Despite all of this, Patty maintains her innocence, framing the conviction as the product of gullible jurors and sensationalist reporters who dubbed her "Poisonous Patty."
Rose Gold, now twenty-three, picks Patty up from prison. In the backseat is a two-month-old baby she introduces as Adam, her son. Rose Gold agrees to let Patty live with her, insisting it will be on her terms. She reveals she has purchased 201 Apple Street, the house where Patty grew up. Patty is horrified: The house holds traumatic memories of her father's physical abuse and her brother David's death by suicide in the basement. Rose Gold cheerfully dismisses Patty's discomfort, citing four generations of family history.
In flashback chapters, Rose Gold recounts the years following Patty's imprisonment. At eighteen, she works as a cashier at Gadget World, an electronics store in Deadwick, Illinois, living alone in a cheap apartment. She is deeply insecure about her appearance, particularly her rotted teeth. She communicates daily with Phil, an online boyfriend she met in a chat room at sixteen, who repeatedly declines to meet in person. She also texts Alex Stone, her only childhood friend and the daughter of Mary Stone, Patty's former best friend and neighbor.
Rose Gold agrees to an interview with Vinny King, a reporter from the tabloid
Chit Chat. She recounts her medical history, explaining how Phil first alerted her that only her mother's food made her sick. At sixteen, Rose Gold found a bottle of ipecac syrup hidden in Patty's sock drawer and pieced together that all her symptoms stemmed from poisoning and malnutrition. She confided in Alex, who helped set in motion the chain of events leading to Patty's arrest. During a visit to Alex in Chicago, Rose Gold overhears Alex mocking her to friends, calling her "tragic." Rose Gold later retaliates by secretly replacing Alex's eyebrow dye with depilatory cream, a hair-removal product. When Alex realizes Rose Gold is responsible, she cuts off all contact.
In August 2014, a man named Billy Gillespie walks into Gadget World and reveals he is Rose Gold's biological father. Patty had told Rose Gold her father was a man named Grant Smith who had a drug addiction and died of an overdose, but Billy is a life insurance salesman in Indiana with a wife, Kim, and three children. Rose Gold is elated and begins building a relationship with the Gillespie family, bonding especially with six-year-old Anna. When the family plans a camping trip to Yellowstone without inviting her, Rose Gold fabricates a diagnosis of stage three Hodgkin's lymphoma, a type of cancer, to guilt Billy into including her. Billy eventually discovers the lie by calling Rose Gold's doctor and tells her she is "just like your mother," ordering her to stay away from his family permanently.
Rose Gold travels to Denver to meet Phil in person, only to discover he is a man of about sixty who lives alone in a cabin. Phil is kind and generous, giving her four hundred dollars for a plane ticket home. Estranged from everyone, Rose Gold sinks into isolation.
In the present timeline, Patty settles uneasily into the house. Rose Gold's bedroom door is always locked, arousing Patty's suspicion. Patty notices her daughter is alarmingly thin and barely eats. When Patty visits Mary Stone to express concern about Rose Gold's weight, Mary accuses Patty of poisoning her daughter again. At Gadget World, Rose Gold's coworker Arnie tells Patty that Rose Gold has been claiming Patty is trying to poison her. Patty is injured when the basement treadmill malfunctions at maximum speed, and someone sets the family's trash can on fire and draws a skull-and-crossbones on the driveway. Rose Gold cooks Patty's favorite meal and eats her own portion without incident, but Patty becomes violently ill. Suspecting Rose Gold poisoned her food, Patty decides she must flee Deadwick with the baby, whom she believes is unsafe with her daughter. She begins contemplating whether the baby might need medical attention, echoing the obsessive monitoring that marked Rose Gold's infancy.
In late 2016 flashback chapters, Rose Gold reveals that she resumed visiting Patty in prison after years of isolation, seeking an honest reckoning. When Patty denies the abuse, then turns verbally cruel before snapping back to sweetness, Rose Gold recognizes the cycle of manipulation and resolves to punish her mother permanently. She purchases Patty's childhood home, orders ipecac syrup online, and begins starving herself to appear emaciated by the time Patty is released. When she learns via social media that Billy's wife is pregnant with another child, Rose Gold is enraged at being excluded from her father's expanding family and devises a plan to punish both parents.
In the present, Rose Gold fails to come home from work one day. The baby begins vomiting, and Patty rushes him to the hospital. Two police officers inform Patty that a letter from Rose Gold has been delivered to Mary Stone, claiming Patty forced Rose Gold to pretend a kidnapped baby was her own and threatened to hurt them both. A search of the diaper bag reveals Rose Gold's hidden phone and a bottle of ipecac syrup planted in the lining. The police reveal the baby's real name is Luke Gillespie, the infant son of Billy Gillespie, reported missing from Indiana two and a half months earlier. Rose Gold kidnapped Luke and presented him to Patty as her own son. Mary Stone arrives and repeats the letter's accusations against Patty. Cornered, Patty makes her first-ever admission of guilt, acknowledging she "sometimes mistreated" Rose Gold as a child, but insists she never harmed Luke and had no idea he was kidnapped. She is handcuffed and arrested.
In the final chapter, Rose Gold narrates from an unidentified foreign country where she has been hiding for a week under a false identity, using forged documents arranged by Phil through a PO box. She reveals the full scope of her plan: After learning of Luke's birth from social media posts by Sophie, one of Billy's daughters, Rose Gold drove to Indiana, entered the Gillespie house while Kim showered, and took the one-month-old from his crib. She faked a pregnancy with a prosthetic suit, stored formula behind her locked bedroom door, and ran breast milk through a pump to make it look used. She added small doses of ipecac to the baby's bottles near the end, enough to make him appear sick but not cause lasting harm. On the morning she vanished, she planted the ipecac and her phone in the diaper bag, added ipecac to the stored milk, and mailed the incriminating letter to Mary. Her plan punishes both parents: Patty faces a second arrest for child abuse and kidnapping, while Billy experiences the terror of losing a child. Rose Gold watches a video of Mary at a press conference declaring she heard Patty confess, a claim based entirely on the letter Rose Gold sent. No one will believe Patty's protestations of being framed, because no one trusts a proven liar. In the final scene, Rose Gold shaves her head with clippers, this time by her own choice, and gazes at her rotten teeth in the mirror without shame, embracing her anger as a source of strength.