If you watched the trailer, you saw that this is a different role for Fontaine, who was usually more demure. Here, she's a scheming femme fatale who'd be just fine in an even darker movie. Joan Leslie's the good girl, and she's dandy, too.
Mel Ferrer plays a painter who gets all the good lines, and it seems pretty obvious that he's gay, though in 1950 nobody would've admitted that.
The movie's directed by Nicolas Ray, and while it's not as well known as some of his films, it's definitely worth a look if it turns up on TV.