"I will not die at their claws and paws," Timothy Treadwell announces to his video camera. "I will be the master, but still, the kind warrior." Earnest, devoted animal activist Treadwell spent some 13 years camping among Alaskan grizzly bears. During periodic returns to civilization, he campaigned for their protection, visiting classrooms and Letterman, co-founding Grizzly People and co-writing Among Grizzlies with Jewel Palovak. A determined, even fanatic crusader, Treadwell met an end he must have imagined and rejected repeatedly: He and girlfriend Amie Huguenard were mauled by a bear in October 2003.

As Werner Herzog's Grizzly Man suggests, it's both awful and predictable that they left a record of their death struggles. For the last five years of his life, Treadwell was an obsessive recorder of his own experience, videotaping 100 hours of his "friends" the bears, as well as his own confessions, complaints and commentaries. "It's good work," he insists, grateful to feel such purpose and connection. "I had no life. Now I have a life."

Grizzly Man contemplates that life, mixing Treadwell's footage with Herzog's interviews with family and friends, as well as bear experts, pilot Willy Fulton (who flew investigators to the scene), even Franc Fallico, the medical examiner who had to make sense of the half-eaten bodies — all to discover why Treadwell crossed what Herzog calls "an invisible borderline." Some interviewees state outright that Treadwell went too far and "got what he was asking for." Herzog makes no secret of his own argument with his subject. As two bears fight in the background, Treadwell offers a play-by-play, then mourns and romanticizes the violence; Herzog is more skeptical, seeing the bears as brutal beasts, males killing their own cubs to be able to "fornicate" with lactating females.

Treadwell "stylized himself as Prince Valiant," narrates Herzog, "fighting the bad guys." These opponents were ambiguous and legion, including poachers, campers, park authorities, even Treadwell's own demons. A one-time waiter, failed actor and recovering alcoholic, he sought a cause, a community in which he could be comfortable. That he found this haven in wild bears suggests a certain desperation. Feeling frustrated and victimized by human women ("I'm nice to them," he says. "I'm a patsy."), he turned to the animals, including a particular female for which he felt a special affection. Look, he exults, "This is Wendy's poop. It was just inside of her."

This is only slightly less discomforting than the scene where Herzog is listening to the death tape (Amie had turned on the video camera but left the lens cap on). Herzog stands with headphones on, back to the camera, which focuses on Palovak's frightened face: She watches, hearing nothing, and then he tells her to destroy the tape, so she will never be tempted to listen to it. In a film so profound about reading absences, making sense of what can only be guessed at, the moment is stunning, both deep and terrible.

Grizzly Man Directed by Werner Herzog A Lions Gate release Opens Friday at Ritz Bourse recommended