Over the course of more than ten years, a mysterious and violent predator committed fifty sexual assaults in Northern California before moving south, where he perpetrated ten sadistic murders. In 1986 he disappeared, eluding capture by multiple police forces and some of the best detectives in the area. Three decades later, Michelle McNamara, a true-crime journalist who created the popular website True Crime Diary, was determined to find the violent psychopath she called "the Golden State Killer." Michelle pored over police reports, interviewed victims, and embedded herself in the online communities that were as obsessed with the case as she was. At the time of the crimes, the Golden State Killer was between the ages of eighteen and thirty, Caucasian, and athletic -- capable of vaulting tall fences. He always wore a mask. After choosing his victims -- he favored suburban couples -- he often entered their homes when no one was there, studying family pictures, mastering the layouts. He attacked while they slept, using a flashlight to awaken and blind them. Though they could not recognize him, his victims recalled his voice: a guttural whisper through clenched teeth, abrupt and threatening.