Embattled passengers Jeremy Glick (Peter Hermann), from left, Thomas E. Burnett Jr. (Christian Clemenson) and Todd Beamer (David Alan Basche) find themselves trapped aboard "United 93."

We've had almost five years to adjust to life in a post-Sept. 11 world.

The passengers and crew of United Flight 93 had about 30 minutes.

In that time, the edge-of-the-millennium America we knew -- well-ordered, self-contained, neatly arranged to allow maximum concentration on life, liberty and the pursuit of happiness -- turned upside down, then disappeared.

Watching "United 93," you can see it happening. But, happily, not in the usual Hollywood fashion. And that's the only happy thing about watching "United 93."

We all know how Hollywood usually treats real-life cataclysms: with spectacular special effects, preposterous plotting and a heaping helping of heart-wrenching, "up-close-and-personal" vignettes designed for maximum manipulative power.

By contrast, "United 93" serves up a gut-wrenching re-creation that represents a triumph -- a heartbreaking triumph, but a triumph nonetheless -- of you-are-there filmmaking.

Writer-director Paul Greengrass ("The Bourne Supremacy") has explored this territory before -- most notably in 2002's "Bloody Sunday," his award-winning, documentary-style account of a 1972 civil rights march in Northern Ireland, during which British soldiers shot and killed 13 unarmed demonstrators.

Understandably, "United 93" hits a bit closer to home.

But both movies employ the same clear-eyed, fly-on-the-wall approach.

And it's no accident that "United 93" carries such a ring -- and sting -- of truth. Interviews with more than 100 relatives and friends of the fallen passengers and crew helped Greengrass construct a "believable truth" regarding the 91-minute flight.

And, on the ground, several air traffic controllers, military members and civilians (including Ben Sliney, who was calling the shots at the Federal Aviation Administration command center on Sept. 11, 2001) play themselves, adding first-hand authenticity while reliving the events of that fateful day.

For much of "United 93," we're either aboard the doomed title airliner -- or with increasingly frantic air traffic controllers trying to keep tabs on one, then two, then three, then four hijacked flights headed who-knows-where.

They discover where when controllers in the Newark, N.J., tower gaze across the Hudson River to see smoke pouring from the World Trade Center.

Meanwhile, United's Flight 93, bound from Newark to San Francisco, has finally gotten off the ground after the usual pesky delays.

Some passengers break out the laptops and get to work. Some chat with seatmates. In the cockpit, the pilot and first officer chit-chat about their families.

And four armed hijackers await the ideal moment to burst into action, seize control of the westbound plane and change its course -- toward Washington, D.C., with the Capitol dome as the intended target.

"United 93" puts us aboard the title flight with the distraught passengers and crew -- people just like us, people who are us -- who decide not to go gently, opting instead to try and prevent an even bigger catastrophe than the one engulfing them.

As one passenger observes during a desperate back-of-the-plane strategy session, "No one is going to help us. We've got to do it ourselves." It's the ultimate ordinary-people-in-extraordinary-circumstances situation.

In keeping with the movie's cinema verité approach, "United 93" unfolds in real time once the title flight gets under way.

And even the most familiar faces on the passenger list (Christian Clemenson, Gregg Henry, Chip Zien) don't stand out, thanks to Greengrass' understated, partially improvisational approach. (The one jarring exception: David "Sledge Hammer!" Rasche, because he's also currently on screen as "The Sentinel's" fictional president.)

Throughout, Greengrass' visual style remains sneakily, subtly spellbinding, with a hand-held camera hovering at the edges of the action, only to plunge in -- with shocking immediacy -- at pivotal moments.

As a result, "United 93" builds the kind of palpable pit-of-your-stomach tension that most conventional thrillers only dream of.

In part, that's because we know (and dread) what's going to happen. But it's also because Greengrass so artfully conveys the swirl of emotions engulfing the passengers and crew -- and, by extension, those of us sitting in the audience, yet somehow sitting right beside them.

From fear to shock to grief and, ultimately, to grim determination -- as some of the passengers rush the cockpit to do something, anything, to thwart the hijackers -- "United 93" offers a cathartic, genuinely moving account of one part of one terrible, unforgettable day.

It's easily the most powerful movie of the not-so-young year, one that honors the victims' memories -- and their inspirational actions -- with a refreshing lack of bombast or manipulation.

Those who think it's "too soon" to ponder such searing events from the stadium-seated comfort of a modern multiplex will skip "United 93," of course.

But not seeing it won't make it any easier to avoid the ongoing, real-life aftermath of the events it depicts in our perilous, post-Sept. 11 world.