“Green Room”

Rated R

***

Opens today at Dole Cannery Stadium 18 and Ward Stadium with Titan XC

With only two major features to his credit, director/writer Jeremy Saulnier has already marked his distinctive cinematic territory. His well-regarded 2013 indie revenge saga, “Blue Ruin,” introduced him as someone who could explore the sordid underbelly of America with an original eye.

Now, in the grim, claustrophobic and equally rewarding “Green Room,” he expands upon that theme while making few concessions to mainstream sensibilities. An ultra-violent thriller set in the world of neo-Nazi punk rock doesn’t exactly scream crossover — even if it does star “Star Trek’s” Patrick Stewart going against heroic type as Nazi-in-chief.

The Ain’t Rights is a struggling punk band whose members — Pat (Anton Yelchin), Reece (Joe Cole), Sam (Alia Shawkat) and Tiger (Callum Turner) — can barely afford to feed themselves or put gas in their junk-heap van, in which they tour the country. So when an equally broke but wonderfully mohawked concert promoter (David W. Thompson) can’t pay them after his show is canceled, he sets them up with a gig on their way back home so they won’t have made the trip in vain.

The one caveat: Don’t talk politics, he tells them.

It turns out the show is at a neo-Nazi retreat in the middle of the woods. It freaks The Ain’t Rights out — they even perform a Dead Kennedys’ anti-Nazi-punk song as noisy protest to the booing throng — but they need the money.

Things take a darker turn when the body of a neo-Nazi girl is found in the dressing room — or green room in entertainment-industry parlance — with a knife in the head, the result of an attack by a fellow believer. The girl’s friend, Amber (Imogen Poots), is so horrified that she’s ready to go against the movement and call the authorities.

The Nazis don’t want the terrified band members or an angry Amber calling the police, so Darcy (Stewart) and his gang decide to shut them up permanently.

What follows is, on paper, standard horror-thriller stuff: our heroes trapped in a confined space with all sorts of evil — human and canine. But Saulnier elevates the ordinary into a tense game of punk rock cat-and-mouse that’s only leavened slightly by a dark sense of humor.

With so many of Saulnier’s indie contemporaries being wooed into the world of big franchises and bigger budgets, let’s hope he doesn’t lose his desire to be unnerving and unsettling.