The IMDB puts it in the "film noir" category, which seem contestable to me. But it's OK anyway. This is the 1956 version, and it's star-studded: Robert Wagner, Jeffrey Hunter, Joanne Woodward, and, whoa, Mary Astor. You'd think she'd make it noir by her mere presence, but unfortunately, her role is pretty minor.
Adding to Mrs. Salad's travails: I couldn't help but blurting out "It's Captain Pike!" every time Jeffrey Hunter popped up onscreen.
Anyway, the plot: Robert Wagner is romancing heiress Joanne Woodward, and (in the opening scene) she announces her pregnancy. The fact that Wagner is a devious lying weasel is obvious to all except her. Unfortunately, he's also demanded that she keep their relationship super-secret. Which will make it easier to… well, you know pretty much what the deal is.
The movie is decently twisty and suspenseful, but you kind of have to put up with 1950's-style over-acting. Jeffrey Hunter's character keeps an unlit pipe clenched between his teeth pretty much 24x7.
According to IMDB trivia, Joanne Woodward once stated that she not only considers this the worst of her movies, but the worst Hollywood movie ever made. Come on, Ms. Woodward, it's not that bad.
Also, Mrs. Salad now believes that Robert Wagner killed Natalie Wood. No argument here.