When a new series of murders spreads fear and panic across her home city of San Francisco, Inspector M.J. Monahan and her partner Reuben Goetz solicit Helen's expertise. Initially reluctant, Helen soon finds herself drawn into the warped perpetrator's game of wits. As the murders continue, Helen realizes that the elusive assailant draws inspiration from notorious serial killers, including Albert DeSalvo, The Hillside Strangler, David Berkowitz, Jeffrey Dahmer, and Ted Bundy. When the murderer begins contacting and even stalking Helen, she and M.J. realize that he is after them, and they enlist the aid of Cullum, who tells them what he knows about the killer.