A teenage couple goes on the run after an attack on the boy's sister. A search leads officers to the girl's grandparents' home, where they find the bodies of the elderly couple and uncover a fantasy killing concocted by the psychopathic lovers.

Police catch a break on three cold case murders when emerging DNA technology makes a stunning match: a 73-year-old man who's been in prison since 1993. Detectives interrogate the frail man whose harmless façade is hiding a murderous psychopath.