IN 1971, a group of presumed radicals broke into the FBI offices in Media, stealing and exposing documents that ultimately put an end to the bureau's Hoover-era excesses.

The "radicals" were never found, in part because the not-entirely-competent FBI was looking for the wrong people in the wrong places - making comically obvious attempts to infiltrate anti-war protest hotbeds in Powelton Village, for instance.

And the perpetrators, as we learn in the absorbing documentary "1971," were not among them.

They escaped the dragnet of usual suspects by being the most usual of people - less like stereotypical hippies than archetypal extras in "Father Knows Best."

Bob, Bill, John, Bonnie, Keith. Those aren't aliases. Those are the actual names of the burglars. You see them in archival footage, strapping suitcases to the top of a family truckster, posing with their kids at the beach.

The perpetrators themselves, gathering to conspire in the home of John and Bonnie Raines, could hardly believe how unradical they were.

Says one: "We were like, whoa, there are little kids in this house."

All were against the war in Vietnam, and some had come to detest the way that the FBI - which Hoover ran (in the opinion of Harry Truman) as his private security force - was shredding the Constitition as it conducted surveillance.

The Media burglars had no experience, no training (the "mechanic" took a correspondent's course in locksmithing), just a shared hunch (correct, it turns out) that if they could steal some FBI files, they'd find evidence of rogue investigations and unconstitutional activity.

"1971" moves briskly through the efficient planning and execution - selecting the soft target of a bureau branch office in Media, waiting until the night of the Ali-Frazier fight, making off with the files, mailing them to news organizations.

Elements of this are amusing - Bonnie Raines cases the office as a college "co-ed" reporting a campus-paper story on opportunities for women, exploiting the bureau's obvious chauvinism. It worked. She was the one member of the eight-person team who was never considered a suspect. Apparently, investigators couldn't get past that homemaker facade.

This is fun, but the movie is perhaps most interesting for the way it examines the group's collective on-the-lam cool. The politics of surveillance may not have changed much, but you can see that the culture has.

They have none of the self-dramatizing posture of the anti-war activist or modern hacker so often celebrated in (pardon the pun) the media.

They did one job, did it well, watched the collapse of Hoover's regime and got on with their "normal" lives. Even today they look like folks you'd see in the landscape department of Home Depot.

No book tour, no gloating, no social-media high-fiving. Instead, there is introspection. They still regret placing their children's upbringing at risk, and one still worries that fall-out from the burglary's revelations have contributed to a toxic public cynicism.

That's an interesting take: That today's jaded citizenry is beyond surveillance-state outrage because they are beyond shock.