A movie out of time and yet distinctly of ours as well, Meek's Cutoff appears in theaters as if in rebuke to our current cinema. Coming after an awards season in which what passed for indie greatness was a calculating grandstander like Black Swan or a live-action caricature like The Fighter, Kelly Reichardt's strange Western seems from another planet: introspective, politically charged, suspicious of glibness. It is an American independent in the true sense of the word, and it may well be the best homegrown movie we'll see this year.

Which won't be the first time critics say that about a Reichardt movie. Still relatively unknown outside of cinephile circles, she's had quite a run in the last half-dozen years. In that time, she's come out with three movies, two of which are stone-cold masterpieces, the third a notch below. With a record like that, Reichardt should be mentioned in the company of fellow indie stalwarts like Gus Van Sant and Todd Haynes. (The latter has served as executive producer for her last three movies.) Her new movie should ensure that she is.

Already much ballyhooed from its festival run, Meek's Cutoff is poised to be her breakthrough. As her biggest production yet, the movie contains the best of her aesthetic, with an unhurried cadence, preference for the murmured and the unspoken, and feeling for environment and man's place in it. But it also opens up new trails for the filmmaker that hint at the course of her evolution as an artist.

Set on the Oregon Trail in 1845, Meek's Cutoff follows the wanderings of a wagon party struggling to find its way through the desert in search of the lush Willamette Valley. The group has been led astray by Stephen Meek, a character based on a real historical figure who was hired by caravans to guide them through the Oregon wilderness but got them lost instead.

Geoffrey O'Brien once wrote that American Westerns had no use for the wilderness—they were always eager to find refuge in town or fort. Meek's Cutoff subverts that tradition. There is not a whiff of civilization here; indeed, the possibility of civilization itself is in doubt. Wandering is depicted as an almost permanent state. Before a word of dialogue is spoken, we see someone etch on a branch: "LOST."

That could very well be the slogan for Reichardt's cinema, peopled as it is by searchers adrift. The road trip gone wrong emerges as a motif. In her debut, 1994's River of Grass, the road trip barely even gets started. A grungy, lo-fi gloss on Bonnie and Clyde, the film finds a mismatched couple, Cozy and Lee (Lisa Bowman and Larry Fessenden), on the run for a crime they think they committed. (They fire a gun at someone in the dark and believe they kill him.) So hapless are they that when they finally do make a run for the border after hiding out in a motel, Cozy and Lee have to turn around at the turnpike entrance—they don't have enough change to get through.

Its dabbling in gunplay and genre may mark it as a product of the mid-'90s indie scene, but it's River of Grass' evocation of loneliness that defines it. This is a movie of dive bars and rat holes. Glum men nurse drinks in the dark, while women dream of escaping the yawning eternity of marriage and motherhood. Redolent of Terrence Malick, not least in Bowman's affectless voice-over (echoes of Linda Manz in Days of Heaven), the movie in its quieter moments has a piercing, Hopper-esque melancholy. In Cozy, Reichardt finds a disquiet that could serve as the wellspring for the rest of her oeuvre.

It took Reichardt another 12 years to produce her follow-up. When she came out with Old Joy at the 2006 Sundance festival, it put her back on the critical map. Another road movie of sorts ("Two Lane Blacktop for vegans" per Dennis Lim's incomparable description), Old Joy tells the story of Mark (Daniel London) and Kurt (indie folk god Will Oldham), two college buddies whose paths have diverged in adulthood. Mark, now married and a soon-to-be-father, does yoga, drives a Subaru Outback, and listens to Air America; Kurt has a scruffy beard, smokes a lot of pot, and skips from one peak experience to the next. The two go on a camping trip, inevitably get lost (thanks to Kurt's flakiness), and eventually find their way to an Edenic hot springs in the Cascades.

Based on a short story by Jon Raymond, who has since become Reichardt's indispensable writing partner, Old Joy is an unassuming gem. Not much happens on the surface, but by movie's end tectonic plates will have shifted, and the end of a friendship takes shape before our eyes. No less attuned to the verdant Northwest mountains as River of Grass was to the sun-baked Florida grasslands, Old Joy elaborates on Reichardt's interest in observing people navigate their environment. Mark and Kurt's hike through the woods is a swoony idyll, as pretty as it is freighted with meaning, subtly juxtaposing immutable and indifferent nature with time's steady erosion of a relationship.

Reichardt's broader perspective is also evident in the film's sneakily political content. If the road movie is as American as the Western and the gangster film, Reichardt's impulse to short-circuit her protagonists' journeys can be read as an implicit political critique. Made in the depths of the Bush administration, Old Joy is a plangent portrait of depressed liberalism. Mark and Kurt are each in their way painfully familiar types, the former the well-meaning liberal bobo dulled by adulthood; the latter, the overgrown stoner, an emblem of an ineffectual and self-indulgent counterculture. Their failure to re-establish genuine rapport signals a more profound disenchantment.

Even more political was her next film, Wendy and Lucy. Topping Film Comment's critics' poll of the best films of 2008, Wendy and Lucy appropriates the tropes of Italian neorealism to depict the Other America. Looking like a Bressonian pixie, Michelle Williams plays Wendy, a woman on her way to Alaska to find work, but whose car breaks down in a small Oregon town. Stuck there for a spell, she ends up losing her dog, Lucy (Reichardt's own pet), and scrambles to stay afloat as her money runs out.

As slender as Old Joy but no less packed with suggestion, Wendy and Lucy is an assured piece of filmmaking. Reichardt is frequently tagged as a minimalist, but that shortchanges her aesthetic. Wendy and Lucy (as with all her movies) brims with grace notes: the ghostly faces of vagrants by a campfire, a pillow shot of birds on a wire against a deep blue sky, the plaintive melody (written by Oldham) Wendy hums throughout the movie. The lapidary sound design is rich with flourishes. Every so often in the distance, we hear the passing of trains, fleeting taunts of escape deferred.

Wendy and Lucy feels almost prescient now with its snapshot of the American underclass. (It was filmed before the economic collapse.) But this isn't a sensationalized portrait of the poor. There is something almost matter-of-fact in the depiction of Wendy's predicament; the slow accretion of unexpected costs and unfortunate turns reflects the way many Americans descend into poverty. Reichardt's respect for the quotidian makes Wendy's plight all the more devastating—that Walgreen's parking lot she loiters in could well be the one down the street. The performances, all stellar (is there a more adventurous actress today than Williams?), have a lived-in quality, naturalism that never calls attention to itself.

Meek's Cutoff might share with Wendy and Lucy Michelle Williams as star and a theme of Americans adrift, but it is undoubtedly a departure for the director. Still handmade by studio standards, it is certainly bigger than her previous movies. (This was not made by a crew of eight camping in the wild, as Old Joy was.)

But beyond the larger canvas, there is something else here, a thrilling and unexpected undercurrent. Williams plays Emily, one of the wives in the caravan, who emerges as the nemesis of the bumbling guide Meek. Her modern, even anachronistic mien contrasts sharply with the blustery fool's. Both are unique in Reichardt's cinema, larger-than-life characters who stake a claim to the foreground and refuse to budge. With Emily, Reichardt seems to be moving beyond the desultoriness and diffidence of her past protagonists: This is her most strong-willed character yet, a woman who refuses to take the blows of circumstance and environment without hitting back.

Combined with the unmistakably allegorical scenario—arrogant cowboy leads his people into endless desert—Meek's Cutoff emerges as Reichardt's boldest movie yet. The wordless gesture and the murmured doubt are still present, but as part of a more combustible mix. There is a defiance here that is new to Reichardt's cinema. The assertiveness becomes her, and it's only fitting for an artist who may be on the verge of venturing into uncharted territory herself.