In Kelly Reichardt's piercing slice of 21st-century life, Certain Women, Laura Dern, Michelle Williams and Kristen Stewart skillfully embody a trio of weary Montanans. Yet the true star of the film is Lily Gladstone, a relative unknown who, until now, has mostly played bit parts or unnamed characters.

Gladstone's scenes fill one of three vignettes that Certain Women draws from the short stories of Maile Meloy. The first focuses on an attorney (Dern) held hostage by a client (Jared Harris); the second is about a troubled mother (Williams) trying to buy a pile of sandstone from a withering old man (a moving Rene Auberjonois); and the final follows a one-sided romance between Gladstone, a nameless rancher, and Beth (Stewart), a beleaguered night-school teacher.

As "the rancher," Gladstone transcends her character's anonymity. While a whiff of calculation—or perhaps just overexposure—occasionally clouds the rest of the cast, nothing in her acting feels preordained, whether she's driving a tractor, trudging through snow or staring longingly across a table in a diner.

Certain Women's moody tales are entrancing, but the film doesn't reach its zenith until it surrenders to Gladstone. Often silent and always hidden under a mountain of baggy clothes, the rancher could have been maddeningly inexpressive, but Gladstone is a master of communicating emotions using only her face. The roguish smile she flashes when the rancher invites Beth to go horseback riding is the most memorable look in the movie.

That's one of the only times Gladstone smiles in Certain Women. But this isn't shocking. The farm where the rancher works seems to exist on an alternate plane of existence—if she has any friends, they remain off-screen. Such bleak loneliness is typical for Reichardt (Wendy and Lucy), who lives part time in Portland and seems transfixed by the gloomy tales of loners living in the Pacific Northwest.

In Certain Women, that gloominess is hard to shake. While the movie shines a spotlight on Gladstone, it's also a showcase for Reichardt, whose sensitive exploration of working-class anguish, old age and sexual identity makes the film feel both profoundly personal and ripped from the headlines. She and Gladstone make a riveting auteur-muse duo. It's because of them that even when Certain Women grows emotionally apocalyptic, you can't turn away. .

CRITIC'S RATING: A-

Certain Women is rated R. It opens Friday at Cinema 21.