In the 1940s, "Baby" Jane Hudson is a world-famous child star. Jane dominates her shy sister Blanche, who, as Jane's understudy and stunt double, longs to have an acting career of her own. It is implied that Jane tends to become jealous when their father shows affection to Blanche. By the 1960s, Blanche has become a serious and celebrated actress, while Jane's career fades into obscurity as she proves unable to transition to adult acting. She appears in smaller roles in Blanche's films, where her scenes usually get edited out. Blanche's career is ultimately cut short by a car accident that paralyzes her from the waist down, after which Jane was committed to a psychiatric hospital. Everyone believes that Jane, jealous of her sister's popularity, had run her over with her car and then gone insane with guilt.