 The middle-age detective Michèle Varin is a troubled and depressed woman in therapy because of the death of her eight years son four years ago. She has many nightmares, all of them related to death, and she has thought in committing suicide. When she is assigned to investigate the murder of a woman found hanging on a tree in the woods suggesting suicide, she becomes obsessed by the case. During the investigations, her state of mind gets worse and she confuses nightmares with reality.