The 1997 arrival of the Hale-Bopp comet spurs the group to prepare for their departure, though their plan to commit mass suicide goes undetected. After an anonymous 911 caller alerts the authorities, Heaven's Gate, deemed the first "internet cult," becomes a media and pop culture phenomenon - but the suicides have a very different effect on those closest to them. Today, former members, loved ones, and experts reflect on the legacy of Heaven's Gate, offering a chilling reminder that indoctrination can happen to anyone.