Reporter Grace Collier (Jennifer Salt) sees model Danielle Breton (Margot Kidder) commit murder in the apartment across the way and promptly alerts the police -- who find no corpse or other evidence of the crime, forcing Grace to crack the case on her own. She teams with private eye Joseph Larch (Charles Durning), with the trail leading to Danielle's once-conjoined twin and a creepy mental asylum in director Brian De Palma's disturbing shocker.