Joan Crawford is a driven actress and compulsively clean housekeeper who tries controlling the lives of those around her as tightly as she controls herself. To prepare to work at MGM Studios, she rises at 4:00 am, scrubbing her face and arms with soap and boiling water before plunging her face into a bowl of witch hazel and ice to close the pores. When Helga, a new maid, thinks Joan’s living room is spotless, Joan finds a minor detail she overlooked and loses her temper.
Joan is in a relationship with Hollywood lawyer Gregg Savitt, but her career is in a downswing. Despite wanting a baby, she cannot get pregnant; seven pregnancies when she was married to actor Franchot Tone ended in miscarriages. When denied an application for adoption, she enlists Gregg’s help to secure a baby. Joan adopts a girl, Christina, and then a boy, Christopher. Joan lavishes Christina with attention and luxuries such as an extravagant birthday party, but also enforces a code of denial and discipline. When Christina is showered with birthday gifts, Joan allows her to choose just one to keep and donates the rest to charity.
When Christina rebels against her mother, confrontations ensue. Joan overtakes Christina in a swimming pool race and laughs at the child; when Christina reacts angrily, Joan becomes enraged and locks the child in the pool house. Later, when Joan discovers Christina wearing her makeup and imitating her, she takes offence and cruelly cuts off chunks of Christina’s hair to humiliate her.
Joan resents Gregg’s allegiance to studio boss Louis B. Mayer and argues with Gregg after a dinner at Perino’s restaurant. Joan guzzles down glasses of vodka and throws a drink in Gregg’s face after he tells her she is getting old. After Gregg breaks up with Joan, she cuts him out of photos. When Mayer forces Joan to leave MGM after theater owners brand her “box-office poison”, she hacks down her prized rose garden with a pair of large gardening shears and an axe.
Joan finds Christina’s expensive dresses hanging from wire hangers, which Joan differs and gratingly prohibits. Enraged, Joan yanks dresses from Christina’s closet, throwing them all over her room, and beats Christina with the metal hanger as she squeals. Declaring the sparkling clean bathroom floor as dirty, Joan throws cleaning powder all over it before striking Christina across the back with the can and wailing for someone to clean it.
Joan sends Christina to Chadwick School. Years later, when a teenaged Christina is caught in a compromising position with a boy, Joan brings her home. Barbara Bennett, a reporter from Redbook, is writing a puff piece on Joan’s home life. After Joan lies about Christina, Christina confronts her in front of the reporter. Joan slaps Christina twice in the face. After Joan questions Christina about why she never complimented Joan as a mother, Christina realizes that Joan adopted her as a publicity stunt and shouts that she is not one of Joan’s fans. Joan tackles Christina to the floor and chokes her, knocking over a lamp in the process, causing Christina to thrash around hopelessly until Joan’s live-in assistant and the reporter pull her away.
Joan sends Christina to Flintridge Sacred Heart Academy, where she is allowed no contact with the outside world. Joan marries Alfred Steele, CEO of Pepsi Cola, moves to New York City, and pressures him to shoulder a great deal of debt to fund their lavish lifestyle. After his death, the board tries to force her to resign, but Joan coerces them into letting her retain her seat by threatening to publicly condemn Pepsi.
After graduating from Flintridge, Christina rents an apartment in Manhattan, where she acts in a soap opera. When Christina is hospitalized for an ovarian tumor, she is temporarily replaced on the show by her visibly drunk mother. Joan dies of cancer in 1977, whereupon Christina and Christopher learn their mother disinherited them both. When Christopher says their mother has managed to have the last word, Christina questions that by asking “Does she?”