PARK CITY, Utah — In the 1980s, Shoko Asahara recruited young Japanese men and women to his little yoga and meditation group. By 1995, the man had devolved into a dangerous cult leader, selling vials of his own blood for followers to drink, and acquiring and manufacturing weapons of mass destruction to prepare for the apocalypse. The terrifying new documentary “Aum: The Cult at the End of the World,” which premiered Friday night at the Sundance Film Festival, traces the innocent origins and eventual deadly repercussions of the Aum Shinrikyo cult in Japan. The media and government dismissed the group...