Jean Gremillon built up a strong reputation as director, and in this film the photography and the acting help keep it together.
Michèle Morgan starts the movie smooching Henri Vidal at an empty soccer stadium, recalling when they first met. And so their love progresses, but then you realize that Morgan has a double life. She is actually married to a very rich man and she inhabits a sumptuous house.
But her heart is set on Vidal, who struggles to start a business. And then - oops! - she does the naughty thing over a torrid weekend with her lover and a lovely baby is born. All's hunky door, Vidal wants to marry her and suddenly the baby takes ill. That is when Vidal finds Morgan dancing in hubby's arms in the high life of Paris.
Vidal is distraught over that discovery but it gets worse: the little girl passes away. Which is when Morgan comes running, bedecked in jewels and furs, and tells Vidal she really loves him. To which he replies with a great one-liner:
"I don't doubt that you love me so much you even forgot you were married to someone else!"
Guess what? Vidal puts his foot down and walks off, having lost lover, daughter, another woman who loves him,. and his business. Morgan loses the impoverished love of her life, cries some on a park bench, and returns to dancing in high society with her wealthy hubby and exquisite jewels.
You could argue that L'ETRANGE MADAME X is all about appearance and reality. I think it's more about the blindness of love and how it cost poor Morgan an unwanted pregnancy and very nearly her lofty social station in life.
I have no idea whether this film provided any inspiration for MADAM X (1966) featuring Lana Turner. If so, both films are equally forgettable.