Margot Kidder is Danielle, a beautiful model separated from her Siamese twin, Dominique. When a hot-shot reporter (Jennifer Salt) suspects Dominique of a brutal murder, she becomes dangerously ensnared in the sisters’ insidious sibling bond. A scary and stylish paean to female destructiveness, De Palma’s first foray into horror voyeurism is a stunning amalgam of split-screen effects, bloody birthday cakes and a chilling score by frequent Hitchcock collaborator Bernard Herrmann.