In the late 1990s, the world was shocked by the mass suicide of 39 members of a new age religious cult who believed their souls would "graduate" to an alien spacecraft behind the Hale-Bopp Comet. Co-founded by Marshall Applewhite, who once called the group “the cult of cults,” and Bonnie Nettles, Heaven’s Gate began in 1975 with the mysterious disappearance of 20 people from a small town in Oregon - and ended in 1997 with the largest suicide ever to take place on U.S. soil. Using never-before-seen footage and first-person accounts from former members and their loved ones, this four-part docuseries is a thorough examination of the infamous UFO cult that stunned the globe with their out-of-this-world beliefs.