Timothy Treadwell was obsessed. He shot vivid tape of himself with massive grizzlies and playful foxes in Alaska's "Grizzly Maze"; director Herzog says, Treadwell felt he was "the grizzly's lone guardian," and that his love would protect him. "They kill, bite, decapitate," Treadwell says, "but it will never be me." But in October, 2003, it was. The 46-year-old and his girlfriend, Amie Huguenard, were killed and eaten by a grizzly. Ironically, their deaths led to the killing of bears he loved. (Treadwell's companion Huguenard remains a mystery, even in "The Grizzly Maze," Nick Jans' book; her family chose not to co-operate with the film.)

A filmmaker for 40+ years, Herzog gravitates toward driven people. (Les Blank's documentary of Herzog is "Burden of Dreams.") The mesmerizing Treadwell reveals a supreme egotist on camera, delighted by his life. After nearly dying of an overdose, Treadwell transferred addiction to bears, claimed they needed him, and that he was "chosen." He often says, "I'll die for them."

Half the movie is from Treadwell's footage; the rest interviews people who knew him. For a surprisingly long time, this delusional man believed dreaming hard enough would bend reality. Treadwell and friend Jewel Palovak founded "Grizzly People," to school children in bear lore; then Treadwell was on "Letterman," as the host asked, "Are we going to read about your being eaten by one of these bears?" And Treadwell's kinship with bears was real; he gave them nicknames: Mr. Chocolate, The Grinch, Sgt. Brown. What made the bears tolerate him?

One man says Treadwell treated bears as if they were "people in bear costumes," and an Aleut museum curator and Harvard doctorate says, "Seeking a primordial encounter, [Treadwell disrespected the bear, inviting death]." Herzog says, "He needed them... more than they needed him... You don't protect a grizzly by standing 3 feet from it." Yet his persevering skill as a filmmaker is impressive; in a riveting battle of two bears, and shots of a baby fox playing on a tarp. Herzog muses, "Studio directors... could never dream of [that]."

Herzog reveals a mix of horror and fascination; Treadwell even shot video of the bear that probably killed him. Knowing an audio record of the fatal attack exists, Herzog wisely doesn't include it. We only know that "Grizzly Man" is a disturbing tale.