Michelle McNamara reflects on the 1984 murder of her childhood neighbor Kathy Lombardo, which she credits with planting the seed for her lifelong fascination with unsolved crimes. Local detectives who worked the East Area Rapist (EAR) case in the ‘70s – and citizen detectives who picked up where they left off – discuss a proliferation of serial rape cases in Northern California at the time, discussing an era when victims were often too ashamed to speak out and sexual crime was minimized in the press and the courtroom.

As Michelle’s loved ones cope with her sudden death, her work to unmask the Golden State Killer lives on. Inspired by McNamara’s interest in genealogy and online DNA testing services, Paul Holes, Chief of Forensics in Contra Costa County, reconstructs the killer’s family tree with the help of genetic genealogist Barbara-Rae Venter. After inheriting Michelle’s 37 boxes of case files, researcher Paul Haynes and true crime writer Billy Jensen work alongside Michelle’s husband, Patton Oswalt, to finish her book, which becomes an instant bestseller. Meanwhile, the release of Michelle’s autopsy report rocks her inner circle.

As 72-year-old former police officer Joe DeAngelo’s arrest unfolds in real time, chilling facts materialize that illuminate Michelle’s prescience in her book’s epilogue, “Letter to an Old Man.” Researcher Paul Haynes and true crime writer Billy Jensen try to learn everything they can about DeAngelo. When Patton Oswalt, Jensen, and Haynes connect with survivors and McNamara’s fellow citizen detective Melanie Barbeau, Michelle’s absence is deeply felt. Series finale.