I'm looking for an old movie in the 1950’s-1960's that I saw when I was a child. I don't know the name of the movie or names of the actors. It was a mystery/drama set in Italy. A blond American woman (Grace Kelly type) meets an Italian man (Cesar De Nova type) who has an autistic daughter in her 20's. The blond woman is about to marry the Italian man when suddenly one day the autistic daughter comes out of her shell and tells the blond woman that she is not his daughter but his wife and that he's done something to her to make her autistic-like. That's all I remember. Please help, I would love to find it and watch it now. Thanks.