On parole for manslaughter, Millie Calloway is hired by Nina Winchester as a live-in maid. She joins Nina's wealthy husband, Andrew, and daughter, Cece, at their home in
Great Neck, Long Island and is given an attic bedroom that can be locked from the outside. Millie is desperate to keep her job as a condition of her parole. She learns that in the past, Nina was institutionalized for trying to drown Cece and attempting suicide by overdose. At Nina's instruction, Millie books Broadway musical tickets and a hotel for the Winchesters; however, Nina then denies having given her these instructions. While Nina takes Cece to ballet camp, Andrew and Millie secretly attend the show, enjoy dinner together, and check into the hotel. Receiving a flood of angry texts from Nina, Millie is comforted by Andrew. The two have sex. They return home, and Millie realizes Nina knows she spent ten years in prison for killing a rapist classmate in high school. Nina finds the musical's playbill and threatens Millie, but Andrew defends her and demands that Nina leave. Andrew and Millie continue their romance. Millie decides to serve Andrew breakfast on an heirloom china plate from his mother, but the presence of Enzo, the groundskeeper, outside the door frightens her and causes her to drop and break the plate. Andrew fires Enzo and tells Millie to pick up the pieces. That night, Andrew asks why she did not wash the broken plate pieces. He later brings Millie to the attic room, drugs her, and locks her inside. Nina picks up Cece from camp and, in a letter to her daughter, explains the truth about her marriage. She fell for Andrew while raising Cece as a young single mother. Early in their marriage, Andrew requested that Nina dye her brunette locks blonde. When she missed an appointment to touch up her roots, he locked her in the attic room until she pulled out one hundred hairs from her scalp; he forced her to do it again after claiming that one strand was missing a follicle. He then drugged her, framed her for attempting to kill Cece and herself, and continued to torment her with confinement in the psychiatric hospital and the attic. When Nina told the truth about her situation, no one except Enzo believed her. Determined to escape Andrew's abuse, Nina hired Millie. She accurately predicted that Andrew would leave her for Millie and believed that Millie could protect herself. As punishment for breaking the china, Andrew gives Millie a shard and demands that she cut her stomach once for each of the plate's pieces. After doing so, Millie stabs him with a knife hidden for her by Nina and locks him in the attic room. Ordering him to pull out one of his front teeth with pliers, Millie forces him to comply by threatening to burn the attic. When Cece suggests that Nina save Millie, Nina sneaks into the house and unlocks the attic door, believing that Millie is still inside. Andrew attacks Millie and Nina, but Millie seems to escape. Andrew attempts to kill Nina, but Millie returns and pushes him off the house's stairwell, killing him. Nina drops a lightbulb, hoping to make it appear that Andrew fell while trying to install it. A policewoman, Jessica Connors, notices that the evidence casts doubt on Nina's explanation for Andrew's death. Jessica mentions that her sister was once engaged to Andrew, and rules his death an accident. After Andrew's funeral, Nina gives Millie a $100,000 check, then leaves with Cece to start a new life. Nina recommends Millie's services to her friend Lisa, who implies that her husband is abusive. Millie asks when she can start. ==Cast==