This is the role Bette Davis went to war with Warner Brothers to get, and which made her a star. She is a Cockney waitress who cruelly breaks the inoffensive student (Leslie Howard) who is in love with her. She doesn't care, but humiliates him because she has the power and it is in her nature
And he would rather have her spite than nothing. It's a psychosexual power game. The adaptation was compromised by censorship. So, Mildred dies of poverty and TB- in the book she is a sex worker who contracts syphilis. The difficulty of condensing an epic meditative novel into an 82m melodrama would have meant trade-offs anyway. It's still transgressive.
Howard is studying anatomy. His own physical injury (he has a deformed foot) has marked him as a victim and is a symbol of his emotional inferiority. She is inarticulate and ordinary but has a sexual charisma that prevails. There is nothing else quite as extreme as this in thirties Hollywood, even precode. Her death scene is phenomenal.
Davis is astonishing. Her accent is a disaster. She is raw and wild, but this is one of her stand out performances. Howard is fine, though too old. But Bette is dominant, as she should be. It's like watching a sadistic, predatory creature torment its victim. It's not a realistic portrayal, it's far more than that: it's horrifying and among the greatest performances of the decade.