In this psychological horror thriller, forensic psychiatrist Dr. Cara Harding (Julianne Moore) is introduced to a patient, Adam (Jonathan Rhys Meyers), who exhibits multiple distinct personalities-all believed to be murder victims. As Cara delves deeper, she uncovers a disturbing connection between Adam's personalities and real unsolved cases, challenging her understanding of science and the supernatural. With each revelation, Cara finds herself entangled in a terrifying mystery that threatens both her beliefs and her life.