The Champagne Murders (1967) Claude Chabrol

A champagne tycoon's (Furneaux) partner (Ronet) suspects his partner's gigolo husband (Perkins) of murders he's been framed for.  

This stylish psychological thriller from Claude Chabrol has such labyrinthine plotting that many critics called it too confusing. Christine Balling (Yvonne Furneaux) tries to convince Paul Wagner (Maurice Ronet) to sell his venerable champagne business to an American company. She asks her husband Chris (Anthony Perkins), who is also Wagner's friend, to help her to persuade the stubborn Paul. While on a trip to Hamburg, Wagner picks up a German girl in a restaurant. The next morning, the girl turns up dead, and Paul can't remember if it was he who killed her. Chris, who becomes aware of the incident, promptly tells his wife, and she tries to blackmail Wagner into signing a deal with Americans. Later, another woman turns up dead, and again Paul was the last person who saw her alive. He begins questioning his own sanity.