In 1979, law enforcement is thrilled when the East Area Rapist (EAR) attacks abruptly stop in Northern California, but in reality, the still unknown assailant has moved south to commit a number of gruesome murders in the Santa Barbara area, known as the "Original Night Stalker" series. The hunt for the perpetrator stalls due to lack of cooperation between jurisdictions and concerns of tarnishing the area’s pristine image, leaving the community unaware of the predator in their midst. Michelle's article chronicling her investigation of the case causes a splash when it's published in 2013.

Michelle and her editors agree to push her book deadline after being granted access to the Orange County Sheriff’s Department’s East Area Rapist / Original Night Stalker (EAR/ONS) room. Poring over 37 boxes of files now occupying her daughter’s playroom, Michelle and her researcher Paul Haynes explore the case of the “Visalia Ransacker,” the perpetrator of a string of burglaries in the early ‘70s bearing striking similarities to EAR.

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.

The victims of the Golden State Killer seek closure following the recent sentencing. Plus, one final boots-on-the-ground investigation brings shocking new revelations to light in the case that inspired Michelle McNamara's fascination with unsolved crimes: the murder of Kathy Lombardo.