What Price Murder? (1957)

Betty Farnwell, a rich widow living in Nice, decides to marry Philippe, a good-looking but self-interested man. No sooner has he got married than he meets bewitching young Eve, Betty's niece, and falls for her. Eve becomes his lover but the trouble is that she happens to be as calculating as he is. As a result she plans to marry a rich young man as Philippe is bound by the ties of marriage. Philippe can't stand such a prospect and decides, with the complicity of the young woman, to murder Betty...