I bought Une Ravissante Idiote to get a chance to see Anthony Perkins speak French - while his accent sounds fairly Anglo-American, it's not too noticeable. Perkins is Harry Compton, a spy set out on a mission to steal some confidential papers from Sir Reginald Dumfrey. Harry's in love with Penelope Lightfeather, whom is coincidentally the seamstress for Dumfrey's wife. Penelope is the inspiration for the title The Ravishing Idiot, as she is not exactly bright. At all.
Brigitte Bardot does a good job as Penelope, as she perfectly captures her aloofness and naiveté. However, she has this terribly strange laugh. That aside it's plain to see why Harry Compton is simply head over heels for Penelope, she's gorgeous and sweet - despite her lack of intelligence. He thinks to himself "She is an idiot, but you love her. You always wanted an English family. She is not English..."
The humor in this film is odd, and just plain silly. But Anthony Perkins is absolutely delightful and charismatic, and the situations in this film are interesting. A nice film to see if you are fans of Bardot and Perkins who work well together (albeit not getting along off-screen), but otherwise I'm reluctant to recommend it to the latter.