First, a warning. This film deals with an incestuous relationship between sisters, so go no further if this seriously squicks you. Based on a true story, Christine (Joely Richardson, "Nip/Tuck") and Lea (Jodhi May, Tipping the Velvet) are maids in a provincial French town in 1932. Widow Madame Danzard (Julie Walters) owns the house and is domineering and demanding. The sisters rarely ever leave the house or speak with the owner or her dull daughter Isabelle (Sophie Thursfield, Oranges Are Not the Only Fruit), and the two have a very intense and emotional bond.

They begin a sexual relationship with one other and seem psychologically troubled, moving towards madness. Eventually they completely snap and brutally murder both Madame Danzard and Isabelle. In the real life case, the older sister Christine was sent to an insane asylum, where she had a complete mental and physical breakdown and passed away within a few years. Younger sister Lea went to prison for 20 years.