On the day of his ninth birthday, Camille announces to his mother, Ariane (Isabelle Huppert), that he wants to go home to his "real" mother. Realising that her son isn't playing games, Ariane agrees to take Camille to an address he gives her, an apartment on the far side of Paris she doesn't know. There lives an enigmatic woman called Isabella (Jeanne Balibar), whose own son, born the same time as Camille, drowned two years ago. Ariane looks helplessly on as Camille throws himself into Isabella's waiting arms. Huppert and Balibar are both outstanding as the competing mothers in Raoul Ruiz's eerie and engrossing mystery which blurs the boundaries between psychological thriller and ghost story.