The Housemaid by Freida McFadden

The story follows Millie Calloway, a young woman recently released from prison, struggling to rebuild her life. Desperate for employment, she accepts a live-in housekeeper position with the affluent Winchester family—Nina, her husband Andrew, and their daughter Cecelia. The job offers Millie a place to stay, but her accommodations are unsettling: a small attic room that locks from the outside.

Initially, Millie is grateful for the opportunity. However, she soon notices Nina's erratic behavior and the tense atmosphere within the household. As Millie becomes more entangled in the family's dynamics, she uncovers disturbing truths about the Winchesters, leading to a series of shocking revelations and a fight for survival.