If you’re looking for a good scare, go see this summer’s version of the “Blair Witch Project,” the documentary titled “Grizzly Man.”

It’s not fiction dressed up to look like a documentary. It’s a documentary that seems almost fictional – the story of Timothy Treadwell, a self-appointed protector of grizzlies who spent 13 seasons in Alaska’s Katmai wilderness filming the creatures. He produces some amazing photography, but in the end, one of the bears kills and eats him, as well as his girlfriend.

Though the attack is captured on the audio portion of his videocam – the lens cap was found still on the camera – we are spared hearing the screams and snapping bones. But the horror is still almost unbearable, in part because his film so clearly shows the implacable ferocity and power of the bears. The narrator, Werner Herzog, early and often refers to the “murder” that is to come. He also interviews the coroner, who gives a graphic description of the bloody wreckage that is recovered from the killer bear’s stomach.

What is really scary, however, is not so much the killing of Timothy Treadwell, who ignored the most basic elements of common sense around wild animals. As one Alaskan who knew him bluntly puts it: “He got what he asked for.”

What’s truly scary is Treadwell himself, a young man with a troubled background involving alcoholism, drugs and a desperate need to find a place in the universe. “Grizzly Man” is the tale of his descent from charming eccentric into madness, including a terrifying clip in which he rants with paranoid intensity about the supposed evils of the outside world and the National Park Service for failing to do more on behalf of the animal kingdom.

Treadwell also films himself, with grizzlies in the background, shouting “I love you” to animals to whom he has given human names. He talks pridefully of the danger he is running, but it never really seems to occur to him that they won’t love him back even if he masters the right grizzly-like behavior. At one moment he films a titanic fight between two male grizzlies battling for the rights to a female; at another he films himself reaching out to pat a grizzly on the nose.

It’s possible, of course, to read too much into the demented actions of a single flawed human. But in the off-season Treadwell made a name for himself as a lecturer in schools across the country, advocating a brand of animal rights ideology that is seldom questioned by those – long departed from the rural world that characterized America until the early 20th century – who like to think of wild creatures as they think of their dogs and cats.

At its craziest, this point of view leads to forms of terrorism in the name of animals and wilderness. The FBI cites more than 1,200 instances of eco-terrorism in recent years, including a graduate student in physics at California Institute of Technology who earlier this year was sentenced to seven years and $3.5 million in restitution for firebombing more than 100 sports utility vehicles at dealerships and homes near Los Angeles.

But as “Grizzly Man” makes explicitly clear, there is a reason that wilderness was once viewed as a deep, dark, dangerous place, while clearing the land was viewed as a sign of progress. Wilderness, and wildness, is deep, dark and dangerous. You might be able to “whisper” to horses, but whispering to grizzlies is another matter entirely.

That doesn’t mean it’s not a good idea to have some wilderness around, but it’s best not to be too romantic or sentimental about it. And those, like Treadwell, who make a virtual religion of it, are courting tragedy – not just for themselves but for the wilderness. As a result of Treadwell’s entirely irresponsible actions, getting too close to the animals and thus habituating them to a human presence – the attacking grizzly is later destroyed, along with another grizzly who happens on the scene.

Mr. Bray is a Detroit News columnist.