Spoiler alert: this review is all spoilers. But this movie is so bad that I don't think it's possible to spoil it any further. A reviewer who has praised the movie asserts that the Anthony Perkins character, Christopher, is in cahoots with the character, or rather characters, played by Stéphane Audran: Audran is Jacqueline when disguised as Christopher's mousy maid and she is the flashy Lydia when not in disguise. Lydia commits a bunch of murders and tries to pin them on Christopher's friend, the character named Paul who is played by Maurice Ronet. Lydia's plan is to benefit financially from the deaths of her murder victims and then live happily ever after with Christopher (why the beautiful and intelligent, albeit ruthless, Lydia would kill in order to be with a loser like Christopher is beyond my comprehension). But if Christopher is in on Lydia's plan, then the scene where he makes a play for Jacqueline and she rejects him makes no sense. Perhaps he could be in cahoots only with Lydia, not realizing that she is also Jacqueline, but that would mean that all it takes for a woman to deceive Christopher is not much more than her wearing of a wig. Christopher's being in cahoots with Lydia would also mean that he would be delighted when he learns that his wife, Christine, played by Yvonne Furneaux, has been murdered, when in fact he is distraught. The entire movie makes very little sense. With the partial exception of Christine, all the main characters are unprincipled and obnoxious people, so it is difficult to have much sympathy for any of them.
Review of The Champagne Murders
