Forecast: anarchy

"I'm a teacher now in a community college," says Mark Rudd, the fabled 1960s activist. "My students will occasionally bring up the war in Vietnam and ask me what my involvement was.

"I'll say, 'Well, I helped found an organization whose goal was the violent overthrow of the government of the United States.' And my students will look at me as if I'm from another planet!"

As well they might. Political dissent still exists in the US, but its forms today are far milder and more diffuse.

The spectacular achievement of "The Weather Underground," the new documentary that contains Mr. Rudd's comment, is its vivid etching of events that unfolded almost yesterday - 30 or 40 years are an eye-blink in historical terms - but seem so fantastic now that viewing them seems as otherworldly as anything a "Matrix" movie has to offer.

The movement chronicled by the film began in the '60s, when the far-left Students for a Democratic Society (SDS) became a driving force behind growing American opposition to the Vietnam War and to the reigning forces of capitalism and conservatism.

In the late '60s, a faction called the Weathermen split away from SDS, implementing guerrilla-style violence meant to counter government-sponsored violence on its own terms and turf. It evolved into the Weather Underground, an outlaw band whose bombings of public buildings earned many of its members places on the FBI's most-wanted list.

"The Weather Underground" tells the movement's tale dramatically and dispassionately, brilliantly juggling the demands of historical accuracy, ideological balance, and sociological perspective. Jumping freely in time, it presents startling juxtapositions of '60s footage and present-day interviews, often involving the same people.

They include Bernardine Dohrn, her husband Bill Ayers, and Naomi Jaffe, a less famous figure with striking insights into the '60s era. Also featured is sociologist Todd Gitlin, an unreconstructed leftist who strongly criticizes the violent rebels who hijacked the SDS he'd helped to organize.

Along with its historical value, "The Weather Underground" is also a terrific movie, energetic, and articulate. It's the don't-miss documentary of the season.

• Not rated; contains violent news footage.