So Sweet... So Perverse (Italian: Così dolce... così perversa) is a 1969 giallo film directed by Umberto Lenzi and written by Ernesto Gastaldi, starring Carroll Baker and Jean-Louis Trintignant. Set in Paris, it tells the story of a wife who plots to get rid of a rich and errant husband but is herself the victim of her accomplices.
Plot
Jean, a wealthy industrialist in Paris, has married Danielle, but she now refuses him. In revenge, he lets himself be seduced by the host's wife at a party. Closer to home, an attractive woman moves into the flat above them, and they sometimes hear an abusive lover rebuke and beat her. Jean combines chivalry and desire by offering to protect her, and soon they are lovers. She is Nicole, and her violent ex is Klaus. She warns him that Klaus will seek to kill him, which happens during a fight. His charred body shows up in a burnt-out car.
Nicole, who in fact is Danielle's lover and accomplice, announces that Jean had given her his share in his company. Danielle begins to be haunted by guilt and, while she is on the phone with Nicole, Klaus creeps in and shoots her dead. In the absence of any better explanation, the police inspector reluctantly accepts suicide. Now rich and no longer at risk of exposure by Danielle, who had hired them, Nicole and Klaus get on a plane for Brazil. Two seats behind them is the police inspector.