Maria, a prostitute, has a morbid relationship with her younger sister Caterina: she is mother, sister and lover to her and never lets Caterina out of the house except to go to dancing school. Caterina reciprocates Maria’s love and accepts her imprisonment” calmly until the day she falls in love with Giovanni, the dancing school janitor. When Maria discovers their relationship, it unleashes a homicidal rage in her…