TeaAtTrianon has a link to the story behind this famous movie
TaT review here:
Barbara O'Neill, who played Scarlett O'Hara's saintly and refined mother, demonstrates her range as the hysterical, paranoid, oversexed Fanny, dripping with venom and religiosity. She would have stolen the show from any other female actress but Bette Davis. Bette is the restrained Huguenot governess Mademoiselle Deluzy, who brings order and dignity into the chaotic household, winning the hearts of the Duc and his children, thus earning for herself the Fanny's hatred.
Wikipedia Link for the Duc includes the conspiracy theory that he faked his death and escaped to Nicaragua to raise another family.
Miss Deluzy later married a minister in the USA and was known in literary circles. His niece wrote the book that the movie was based on.
Unlike nearly all the movies based on Jane Eyre, which except for Zefferelli's version show a nice looking woman as the self described plain Jane, in this one Bette Davis indeed appears plain: ah but with luminous eyes.
The movie is not on line for free, but the Ebook can be read at Project Gutenburg (AUS):