Plot of Fear tells the story of a decadent weekend party full of orgies and drugs on the outskirts of Milan. After two deaths occur Inspector Lomenzo interrogates one of the guests, a fashion model who becomes his informant, as well as his lover. Clery reveals that after a “wildlife orgy”one of the hosts tried to jokingly feed one of the prostitutes to a tiger but she got so frightened that she died of heart attack. In his attempt to find a connection between the victims, he investigates a cutting-edge security and surveillance firm whose director has secrets of his own to hide.

Lise, a mentally unbalanced middle-aged woman, travels from her home in Hamburg, Germany to Rome, Italy where she embarks on a fatal destiny that she had helped to arrange for herself – a premeditated search for someone, anyone, with whom she could form a dangerous liaison. Lise meets a variety of people during her journey and stay in Rome who include Bill, a lecherous British businessman that she meets on the plane to Rome who tries to seduce her; Carlo, a young man whom Lise tries to know more about; an elderly Englishwoman named Mrs. Fiedke whom Lise bonds with to go shopping; and Pierre, a Frenchman who picks up Lise hoping to seduce her as well.
The film is told in a non-linear narrative as throughout the film are scenes of the local Rome police interviewing all the people that Lise interacted with as well as investigating the reasons for her strange behavior that led up to her own murder.