The inception of the group dates back to 1970s Oregon, where founding members Bonnie Nettles and Marshall Applewhite begin to recruit individuals interested in end-of-the-world Christianity, new age religion and UFOs.

Bonnie and Marshall -- who call themselves Ti and Do -- enforce strict rules of no family communication; after Ti dies from cancer in 1985, a distraught Do briefly allows members to visit their families, and a few consider leaving the group for good.

Using a sci-fi TV series to help bolster his teachings, Do encourages asexuality and submission, and he even initiates voluntary castrations; having dwindled in number, the group starts recruiting again, but they're met with derision and skepticism.

The arrival of the Hale-Bopp comet spurs the group members to prepare for their departure; after the authorities are alerted, Heaven's Gate becomes a pop culture phenomenon, but the suicides have a very different effect on those closest to them.