Clocking in at under 12 minutes, Kenneth Anger’s 1969 film Invocation of My Demon Brother is a terrifying journey into the rotten underbelly of the 1960s. Featuring a host of notorious San Francisco denizens—such as Bobby Beausoleil, later convicted for his involvement with the Manson Family murders, and Church of Satan founder Anton LaVey—Invocation has been the source of much speculation and misinformation. And while this unforgettable screed of existential dread gives viewers a peek into both Anger’s own personal demons and the horrors lurking beneath the counterculture, it has never been explored within the context of the horror genre—until now.

Drawing on original interviews (including a new, in-depth interview with Beausoleil), unpublished archival research, a shot-by-shot analysis of the film, and the author’s personal relationship with the late director, Jarett Kobek’s Invocation of My Demon Brother illuminates the cultural significance—and unique horrors—of Anger’s seminal film and traces the myriad events leading up to one of the most notorious murders in American history.