In 19th-century Normandy, a young and ambitious chambermaid named Célestine, portrayed by Léa Seydoux, takes on the challenging duty of serving the Lanlaire family, which includes a bitter wife and her perverse husband. Monsieur Lanlaire has a notorious reputation for his inappropriate advances towards his chambermaids, while Madame Lanlaire is known for her harsh treatment and frequent termination of her servants. As Célestine settles into her new role, she also encounters the other household staff, including Marianne, the overweight cook, and Joseph, the mysterious groom played by Vincent Lindon, with whom Célestine shares a complex connection.
Throughout the narrative, Célestine reflects on her past experiences, such as a position where she served a middle-aged woman, who faced considerable humiliation at a train customs checkpoint after being forced to open a box that revealed her private toy. Another noteworthy job involved caring for the sickly young Georges and his affectionate grandmother; despite resisting his initial romantic advances, Célestine ultimately engaged with him, only to be horrified as he succumbed to his illness during their intimate encounter. This traumatic episode becomes a turning point for her, leading her to leave that position emotionally scarred.
Within the oppressive environment of the Lanlaire household, Célestine finds herself frequently chafed by Madame Lanlaire's unreasonable expectations. Madame Lanlaire often derides Célestine for any perceived shortcoming and even prohibits her from attending her mother's funeral. Meanwhile, Monsieur Lanlaire becomes fixated on Célestine, who skillfully rebuffs his advances while secretly plotting to gain the upper hand in her manipulations. Célestine's aspirations are further complicated by Captain Mauger, another figure who takes an interest in her, having recently decided to bequeath his estate to the servant Rose after her previous master left her for his infidelity with the maid.
As the story unfolds, Célestine finds knowledge and fellowship among the women of the village, including the local abortion provider. During a poignant exchange with Marianne, Célestine learns about Marianne's painful past, revealing her prior attraction to an old master and the devastating consequences she faced when the relationship led to unwanted pregnancy. This revelation touches Célestine deeply as Marianne shares her own current affair with Monsieur Lanlaire, highlighting the cycle of exploitation. One unsettling night, Célestine hears terrifying screams emanating from the nearby forest, adding to the mounting tension in her life.
Further complicating matters, Célestine learns of Joseph's troubling views and ambitions, as he expresses disdainful and anti-Semitic sentiments. His treacherous dream includes creating a meeting place for right-wing extremists, and he sees Célestine as a key component in his plans. While engaging in gossip with her peers, Célestine learns of a shocking crime involving the violent demise of a local girl, leading her to suspect Joseph's involvement, igniting both fear and fascination within her.
The situation escalates when Rose dies, compelling Captain Mauger to confess his disappointment in her inability to uphold her duties after becoming a mistress. He proposes a similar arrangement to Célestine, which she considers with shrewdness while plotting her next move. Célestine's relationship with Joseph intensifies, culminating in a secret affair. After a tumultuous experience, they conspire to steal silverware from the Lanlaire household, a crime conveniently attributed to professional thieves when discovered.
Despite extensive investigations by the police, no evidence points to Joseph, who garners the trust of the Lanlaire family due to his long-standing loyalty. Eventually, the case goes cold, and Joseph decides to leave his position. As Célestine awaits his return, she ingratiates herself with Madame Lanlaire, even fabricating a story of engagement to justify her departure. When the moment arrives and she receives a signal from Joseph, she realizes the full extent of her manipulation and the depth of their tumultuous connection. Recognizing Joseph’s devilish charm yet feeling ensnared by him, they venture into the night towards Cherbourg, their future shrouded in uncertainty.
