Kimberly Gilbert and Michael Russotto in a scene from “A Bright New Boise” at Woolly Mammoth Theatre. (Tracy A. Woodward/THE WASHINGTON POST)

The saddest moment on a Washington stage this year also happens to be one of the most exhilarating. It occurs in Act 2 of “A Bright New Boise” — playwright Samuel D. Hunter’s unsparing account of the hunger pangs in the barren American gut —when the blandest of bland men, superbly played by Michael Russotto, comes to the vague awareness that he’s responsible for no small amount of suffering.

“I think I might be a bad person,” moans Russotto’s Will, bathed in the harsh fluorescent light of a break room in a big-box Idaho crafts store. As he cups his face in his hands and begins to sob, you are made to feel enormous pity for him, despite the reckless piousness with which he’s consoled himself, a religious certitude that has contributed to terrible hurt for others in his life.

Nothing is pretty about “A Bright New Boise,” a play that marches in the footsteps of Sam Shepard’s acid comedies, set in the weird American West. Yet, you’ll find substantial beauty in Woolly Mammoth’s production, beginning with the mysterious, magnetic ordinariness Russotto manages to project, and extending to the exceptionally fine-tuned performances director John Vreeke elicits from the rest of the cast: Kimberly Gilbert, Joshua Morgan, Emily Townley and Felipe Cabezas. Michael Willis and Michael Glenn, meanwhile, are suitably tranquilizing as a pair of dull types from the central office who drone monotonously on a videotape on the employees’ break room TV.

Even Misha Kachman’s detailed set, with parking-lot light poles towering above the store like electric redwoods, seems to elevate utilitarian American design to something like accidental art. (The lighting by Colin K. Bills is also used to optimal effect.) In a workplace that serves as a bulwark against imagination, it’s no wonder Hunter’s characters include Cabezas’s Leroy, a college art student and part-time salesman whose portfolio largely consists of T-shirts emblazoned with obscenities.

Corporate torpor is a popular motif in American plays and films, and frequently takes on a sinister cast, whether in the social comedies of Neil Labute (“Reasons to Be Pretty”) or a movie thriller such as “One Hour Photo” — set in a discount store so sanitized it makes a Target look like an outdoor flea market. So Hunter, a New York playwright who was raised in rural Idaho, is not unveiling a dehumanizing environment that we have not seen before. You’ll no doubt find familiar the undercurrent of menace that infuses the banal decor of the Hobby Lobby, the chain store in which the play takes place.

But Hunter has such highly sensitive antennae for the look and rhythm of mundane places that “A Bright New Boise” develops an authentic texture, separate from other pieces in its genre. Each voice in the play, with Vreeke’s encouragement, is distinct and remains true to itself. The singsong of the suits on closed-circuit; the potty mouth of the store manager, Townley’s Pauline; the high-pitched anxiety of Gilbert’s socially inept loud talker, Anna; the disconcerting lack of affect shown by young Alex, expertly embodied by Morgan; these collectively contribute to the mosaic Hunter assembles, which feels at once all too emblematic of a desiccated culture — and all too creepy.

The play, though, is essentially Will’s. In the guise of the kindly looking Russotto, Will’s an innocuous presence, a guy no more special than the styrofoam and cardboard stuff filling the store aisles. He’s hired on the spot by Townley, terrific here as a supervisor with more on the ball than you’re initially led to think. Soon enough, some disturbing history is revealed about Will’s association with a renegade church in northern Idaho — and a horrible past incident involving a young parishioner that turned the congregation’s members into pariahs. But escape into anonymity is not the entirety of Will’s mission at the Hobby Lobby. It’s a more personal quest whose nature won’t be divulged here.

The piece, in a sense, is about the havoc that can be wreaked by blind, even vengeful faith, in this instance to a church wrapped up in a prophecy of apocalypse. As the drama unfolds, Will slowly lets his co-workers in on his vision of the Rapture that he’s depending on coming soon, an End of Times that’s bleak and fierce and punitive — a satisfying fantasy for a man who seems to have known nothing but disappointment.

The playwright, fortunately, leavens the lugubrious aspects of Will’s fervor with the risible absurdities of miserable minimum-wage workers forced to keep the paying customers happy. And always, the production benefits from the presence of Russotto, a veteran Woolly Mammoth actor who might be giving the best performance of his career. It’s both delicate and dark, a portrayal that reminds that no matter how long you’ve lived, you never, ever know what’s really going on in someone else’s head.

That inscrutability is kind of a charm for Russotto, for in Will’s desperate dilemma — muddled about everything, except the end of the world — you feel for him, to a surprising degree. Watching as Russotto stands in the Hobby Lobby parking lot, screaming Will’s curses on humanity over the deafening sound of the interstate, you don’t sense a man’s malevolence as much as his petulant surrender.

A Bright New Boise

by Samuel D. Hunter. Directed by John Vreeke. Set, Misha Kachman; costumes, Ivania Stack; lighting, Colin K. Bills; sound and music, Chris Baine; video, Aaron Fisher; dramaturge, John M. Baker. With Michael Willis, Michael Glenn. About two hours. Through Nov. 6 at Woolly Mammoth Theatre, 641 D St. NW. Visit or call 202-393-3939.