Millie Calloway, on parole for manslaughter, takes a job as a live-in maid for Nina Winchester, moving into the Winchester home in Great Neck, Long Island. She is given an attic bedroom that locks from the outside, a detail that unsettles her as she meets Enzo, the groundskeeper who bluntly tells her she doesn’t belong there. Despite Nina’s volatile moods, Millie clings to the job as a necessary condition of her parole, hoping it will keep her life on track. Through Millie’s early days in the house, we learn that Nina’s past is troubled: years earlier, she was institutionalized after trying to drown Cece and after an overdose attempt, a history that casts a long shadow over the present.
At Nina’s insistence, Millie arranges Broadway tickets and a hotel stay for the Winnchers, though Nina later denies asking for the favors. While Nina takes Cece to ballet camp, Andrew and Millie secretly attend the musical, share a meal, and check into a hotel. Millie returns home to a flood of hostile texts from Nina, and a growing closeness forms between her and Andrew as they begin a quiet romance. Back at the house, Millie discovers that Nina is aware of her decade-long prison sentence for a high school crime, and a sense of danger intensifies when Nina’s car is reported stolen and nearly draws Millie into trouble again.
The mood shifts when Nina finds the playbill and confronts Millie, but Andrew stands up for her, demanding that Nina leave. The relationship between Millie and Andrew continues to deepen, even as the couple’s secrets threaten to unspool. Millie’s plan to bring Andrew breakfast on an heirloom plate from his mother is interrupted by Enzo’s ominous presence outside the door, causing her to drop the plate in fright. Andrew fires Enzo, comforts Millie, and later escorts her to the attic, where he gets her drunk and locks her inside.
Feeling a sense of fragile freedom, Nina decides to tell Cece the truth in a letter. She reveals how she fell for Andrew while raising Cece as a single mother, but how the marriage unraveled as Andrew proved controlling. He demanded that Nina dye her hair; when she forgets, he locks her in the attic and imposes punishments that include hair-pulling and confinement, followed by drugging and a false narrative about crime she did not commit. Nina’s account is not universally believed, but Enzo is the only one who truly believes her, though even he cannot coax Nina to leave the abusive situation. Driven by a resolve to escape, Nina hires Millie, hoping she can provide protection from Andrew’s power and manipulation.
The stakes escalate when Andrew imposes a cruel punishment for breaking the china: he forces Millie to cut her own body with a shard and demands more until she finally retaliates. She stabs Andrew with a concealed cheese knife, then forces him to submit to further coercion—she asks him to pull out a front tooth with pliers and uses the opportunity to destroy more of the china and threaten a fire to coerce his cooperation. Cece’s plea to save Millie appears, briefly shifting the momentum, as Nina slips into the house and unlocks the attic door, sensing Millie’s peril. A confrontation ensues: Andrew attacks, but Millie seems to escape, and he turns his violence toward Nina after she refuses to resume the life they shared. In a final act of defiance, Millie reappears and pushes Andrew down the stairs to his death, while Nina drops a lightbulb to feign an accident and misdirect the danger.
A police inquiry lingers, with a detective spotting inconsistencies in Nina’s version of events. It is revealed that Nina’s sister was once engaged to Andrew, a connection that complicates the investigation and helps frame the death as an accident. After Andrew’s funeral, Nina leaves with Cece, handing Millie a substantial check and offering a referral to a friend who is dealing with an abusive partner. Nina suggests Millie could start anew, and Millie, hopeful, asks when she can begin.
