"SHOCK AND AWE" are some of the first words heard in Green Zone, which takes place in Baghdad in March of 2003. Kicking things off with a literal bang, director Paul Greengrass begins with a street-level view of the shocking and awesome destruction that was unleashed on the city—and instead of those familiar, sterilized, long-distance glimpses of the attacks, we see living room walls shudder and crack as explosions bloom from nearby streets. It's visceral, overwhelming, and terrifying.

Moments later, we see the flipside of the 2003 invasion: After risking his life to secure a location that he's been assured contains WMDs, Chief Warrant Officer Roy Miller (Matt Damon) finds nothing. "Site's empty," are the words uttered, in resignation and frustration, and damned if they don't seem a lot more accurate than "shock and awe" when it comes to describing the clusterfuck that was/is Iraq.

Damon's Miller is a lot like Jason Bourne, and Green Zone is a lot like the Bourne flicks—no big surprise, considering Greengrass also helmed The Bourne Supremacy and The Bourne Ultimatum. Adapting journalist Rajiv Chandrasekaran's book Imperial Life in the Emerald City, screenwriter Brian Helgeland's narrative jumps between hard-hitting action sequences and less-than-hard-hitting scenes of politically loaded dialogue.

Miller's job, as Green Zone begins, is to track down WMDs in Baghdad, thus justifying the American invasion. The only problem—and you'll never see this coming!—is that whenever he gets to a place where WMDs are supposed to be, there's jack shit. Miller, likeable and determined, starts asking questions, quickly finding a few people who may be allies or may be enemies: CIA badass Martin Brown (Brendan Gleeson), Wall Street Journal reporter Lawrie Dayne (Amy Ryan), and Pentagon bureaucrat Clark Poundstone (Greg Kinnear, sparring with Damon for the first time since the duo played conjoined twins in the Farrelly Brothers' somewhat less-ambitious film Stuck on You).

Though Green Zone's details and characters are (mostly) fictitious, its broad strokes aren't: "Don't be naïve" is a mantra said twice, and for all the film's action, we're frequently reminded of some Very Important Issues. By the time former president George W. Bush's ill-advised "mission accomplished" press conference gets yet another rebroadcast and an Iraqi lectures Miller ("It is not for you to decide what happens here!"), it's as if Greengrass is daring you to write off Green Zone as The Bourne Invasion.

But this is pop, first and foremost: Green Zone sets out to be an action thriller, and it succeeds. The film works when it deals not with simplified moral quandaries, but rather when it's dominated by Greengrass' action chops. His camera feverish and eager, Greengrass' action scenes burst with momentum and catharsis—while Green Zone is occasionally harrowing and smart, it's at its best when its just gripping.