Kenneth Bianchi, one of the two serial rapists and killers who terrorized the Los Angeles area in the late 1970s, is giving police station interviews to psychiatrist Samantha Stone, who has disquieting lifestyle issues of her own. It falls to her to delve into the details of the case to determine the veracity of Bianchi’s claims of multiple personality disorder, but in so doing, she is forced to relive the horrific crimes, one of which occurs at her very doorstep.

Kenneth Bianchi is a security guard whose attempts to become a police officer are repeatedly thwarted. He moves to California to live with his cousin Angelo and dates a string of women, becoming increasingly preoccupied with sex. Eventually the cousins decide to start an escort agency. After violently killing a prostitute they thought had betrayed them, Kenneth and Angelo begin committing a series of crimes that become a media sensation.