Build a movie plot around this: How did Nix Sr. obtain information about Cain's childhood? Through first hand accounts. He abused his own son to study the emerging personalities.
Dr. Carter Nix (Lithgow) is a respected child psychologist. His wife Jenny (Lolita Davidovich) is an oncologist. Carter takes time away from his flourishing practice to care for their two-year-old daughter, Amy. Jenny becomes concerned that Carter is obsessively studying their child; he regards her like a scientist tracking the development of his creation.The audience quickly learns that Carter suffers from multiple personality disorder. His multiples are Cain, a streetwise hustler, Josh, a traumatized little boy, and Margo, a middle-aged mother figure. Carter/Cain is killing young mothers to procure their babies and toddlers.In a side story we learn that Jenny is having an affair with Jack Dante (Steven Bauer), the widower of a former patient. She fell in love with him and had a relationship with her years ago, but he left her. Now he's back, and she plans to leave Carter and run off with him. When Carter accidentally discovers their tryst, he descends all the way into his madness. Carter/Cain begins leaving subtle clues for the police that Jack is the real killer.Next Carter attempts to kill Jenny by submerging her car in a lake. She pulls herself out and confronts Carter at their home. Unable to find Amy, Jenny demands Carter tell her where she is. Carter replies that she is with his father whom Jenny knows has been dead for years.Carter is apprehended for attempted murder. The police bring Dr. Lynn Waldheim (Frances Sternhagen) to interrogate him. Though enduring hypnotherapy, Dr. Waldheim interviews Carter and informs the police that she co-wrote a book with Dr. Nix Sr. called Raising Cain about a boy with multiple personality disorder. The doctors agreed that patients with MPD seemed to share certain childhood traumas, but there could be no ethical way to test these theories through direct clinical observation. Dr. Nix Sr. had extensive detailed knowledge of Cain's childhood torture, including a few taped recordings of their sessions. However, Dr. Waldheim was never allowed to meet Cain. She pieced the...