I'll Be Gone in the Dark is an American true crime documentary television series directed by Liz Garbus, Elizabeth Wolff, Myles Kane and Josh Koury, revolving around Michelle McNamara as she writes a book about and investigates the Golden State Killer.

[2] Michelle McNamara lived a quiet life, but as her family slept, she spent the night investigating and writing a book about the Golden State Killer, delving into the world of online chat rooms and crime blogs.

[3] The title of the book and documentary is taken from a threat made by the Golden State Killer during his 1976 attack upon his tenth victim, then-15-year-old Kris Pedretti, to whom he said, "Do what I say or I'll kill you and be gone in the dark".

[4][5] In April 2018, HBO Documentary Films acquired rights to I'll Be Gone in the Dark by Michelle McNamara, with plans to adapt the book into a docuseries, with her husband Patton Oswalt serving as an executive producer.

The website's critical consensus reads, "Director Liz Garbus smartly centers I'll Be Gone in the Dark around the late Michelle McNamara's passionate efforts, weaving together a heavy, but important tapestry of trauma, obsession, and survival.