Margot Kidder is Danielle, a beautiful model separated from her Siamese twin, Dominique. When a hotshot reporter (Jennifer Salt) suspects Dominique of a brutal murder, she becomes dangerously ensnared in the sisters’ insidious sibling bond. A scary and stylish dissection of female crisis, Brian 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 Alfred Hitchcock collaborator Bernard Herrmann.