Possession is a 1981 FrenchGerman horror drama directed by Andrzej uawski and starring Isabelle Adjani and Sam Neill. The plot obliquely follows the relationship between an international spy and his wife, who begins exhibiting increasingly disturbing behavior after asking him for a divorce. Filmed in Berlin in 1980, the film debuted at the Cannes Film Festival, where Isabelle Adjani won the award for Best Actress for her performance. The film later developed a cult following.
Though Mark would rather stay with Anna and work things out, he turns the apartment and custody of their young son, Bob, over to her. Living alone, he begins to obsess over her, making dozens of calls, and seemingly going mad. He pays a visit to their flat only to find Bob alone, unkempt, and neglected. When Anna returns, he refuses to leave her alone with the child but attempts to make amends. He stays at the apartment to care for Bob but Anna leaves in the middle of the night.Mark receives a phone call from Annas lover, Heinrich Heinz Bennent, telling him that Anna is with him. He then gets Heinrichs phone number from Annas friend, Margie. The next day, Mark meets Bobs teacher, Helen also played by Isabelle Adjani. She looks exactly like Anna but with brilliant green eyes and is calm and kind where Anna is hysterical. ........
Source: Wikipedia