Undertow begins with a faux-disclaimer telling us that what we're about to see was made in cooperation with local law enforcement and the surviving family of John W. Munn (Dermot Mulroney). Soon thereafter, it launches into a chase sequence, with teenager Chris Munn (Billy Elliot himself, Jamie Bell) on the run from your garden-porch-variety shotgun-wielding hillbilly with a hunting dog. The opening credits unfurl in retro style, with freeze frames, zooms and actor names accompanied by those of the characters they play. Chris brutally impales his foot on a nail (Bell apparently did the same shortly before shooting, so that might just be a real wound you see him sporting on screen) and is caught and brought home by his father, the aforementioned John W. Munn.
Dad is mad that Chris' shenanigans interrupted little brother Tim's birthday party; Chris is mad right back, exclaiming that it isn't a party when there aren't any other guests. The Munns live an isolationist lifestyle, it seems. John works part time as a taxidermist, and he and Chris raise pigs. Tim (Devon Allen) is a sickly kid unable to do much, and no one seems to have told him that his habit of eating dirt and paint probably contributes to his frequent bouts of regurgitation.
So, George Washington fans, that's your congenitally sick kid. But what if you preferred All the Real Girls? As it happens, Chris was running from the shotgun hillbilly because he was romancing the guy's daughter, Lila (Catch That Kid's Kristen Stewart), who looks a lot like Girls' Zooey Deschanel. There's also a scene of Chris in wet underwear, another motif Green seems to groove on.
Green doesn't depend on the old ideas, fortunately--they're window dressing for the real thrust of the drama, which gets going with the arrival of Deel (Josh Lucas), John's long-estranged brother who has just been released from prison. Though the bad blood between the two hasn't fully evaporated, John lets him stay. But since Deel is played by Lucas, you just know he has to be a bad guy, and sure enough, he immediately starts trying to play father and sons against each other. Things turn dark, and the kids end up running for their lives. After that, Green slows things down a little, occasionally building toward a climax that some viewers have called ambiguous, though it seemed perfectly clear to this writer.
Green's primary agenda in all his films is to depict the South, and particularly Appalachia, in a realistic fashion, getting things right that more expensive productions based out of New York or Hollywood either gloss over or grossly caricature. Lila's dad aside (let's be honest, some hillbillies do fire shotguns), none of the folks you'll ever see in a Green film are Klansmen, or televangelists, or married to their sisters. In Undertow, every character seems so well-studied that there really are no extras. Even the most minor performances, from a simpleton tow-truck driver to a dreadlocked bum who hangs around the harbor, come complete with hints of a rich inner life; had the story suddenly swerved to focus on them instead of the Munn boys, one gets the sense, the movie overall would be no less involving. It's easy to imagine Green working with actors the Mike Leigh way, taking weeks to build and improvise the characters. The fact that the British Jamie Bell is utterly convincing not just as a Southerner, but as a Southerner from a specific region, is testament to that.
One thing that isn't authentic to the South, though, is the music. No doubt Green wanted to avoid Deliverance clichés by using banjos, but Philip Glass? And the Brooklyn Youth Chorus? One envisions those Pace Picante salsa commercials that insist upon Texas ingredients: "This here music was made in New York City!" "New York City?!!!" Hey, if the Coen brothers can get the music right (in O Brother, Where Art Thou?), a true Texan (and Tarheel) has no excuse.
It's interesting to note that the time period represented in Undertow is utterly non-specific. The opening credits are '70s-style, the United Artists logo is not the modern-era one, John drinks Nehi soda from glass bottles, and the only TV we see uses an antenna and displays hymn-singing ladies with really poofy hair. It's possible all this stuff is still commonplace, especially among social recluses, but add in the revenge-flick elements, and it seems there's a deliberate retro theme. One scene in a junkyard even plays like an homage to The A*Team, a show that may well prove to have been a formative influence on filmic auteurs of a certain age--it's also referenced in Napoleon Dynamite.