The best thrillers blast through fear and demand action.

They drag you to the edge of your seat. They make you shout at the screen, or at least mutter your response to whatever life-threatening scenario is unfolding before you. You’re there. You’re involved. You’re trying not to panic, trying to avert your eyes, hoping to reason/scheme/plan your way out of the same jam confronting the hero or heroine on the screen.

“Green Room” does that. A ferocious, bloody, primal and pitiless gut-punch of a movie, it packs a struggling band in the green room (backstage waiting area) of a club they have underestimated at a gig that they never, ever should have taken.

They’ve witnessed a stabbing. They’ve tried to call the cops. But management, and its minions, aren’t having it.

The threat here isn’t zombies or werewolves or vampires. The bad guys are Nazi skinheads, violent men, gun nuts, fanatics. But like all gangsters, they’re also menacing morons with impulse control issues. If these over-matched, scared-witless musicians can catch their breath, maybe they can think their way out of this.

Actor/musician Anton Yelchin is Pat, the guitarist for the Ain’t Rights, a DC area punk band at the end of a busted tour, siphoning gas out of cars in packed parking lots just to get home from Washington state. Alia Shawkat is the bass player. They’re the common sense members of the group, and the best at siphoning gas.

A guilt-ridden promoter (David W. Thompson) offers them a chance to make some road trip money, in the woods at a club off the beaten path, somewhere in Oregon. Yeah, it’s a skinhead club. But it’s a gig.

“They run a tight ship, except it’s a U-boat.”

The Ain’t Rights soak up the jackboots, the SS insignias and Confederate flags. First set, they salve their consciences by provoking the rougher-than-rough crowd with a cover of the Dead Kennedys’ “Nazi Punks.” But backstage, they walk in on a murder scene.

And that’s when it all goes south.

They can’t get a reading on the club manager (Macon Blair). Is he threatening them, holding them hostage, protecting them?

“We’re sorting it out,” isn’t comforting. Out comes the first gun, and no, they cannot leave, cannot speak to the cops.

And the one hostile eyewitness from the skinhead community (Imogen Poots) trapped in the green room with them cannot decide if she’s friend or foe.

The pacing of writer-director Jeremy “Blue Ruin” Sailnier’s film gives it the feel of both victims and those holding them making this up on the fly. Everybody on scene is improvising their reaction to this situation.

There’s no over-explaining, little stating of the obvious.

“You’re trapped. That’s not a threat, it’s a fact.”

Patrick Stewart rolls in as the club owner, a quietly menacing leader of “a movement, NOT a (political) party.” This is “manageable.” He just needs to get the right people on scene, his “Red Laces” squad — the Survivalist Northwest’s version of Hitler’s Brown Shirts.

Meanwhile, in a room with one exit guarded by a hulking brute with a gun, the band is panicking. What can skinny young pacifists — well, save for the hothead lead singer (Callum Turner) — do in the face of Nazi brute force, Nazi machetes, Nazi guns, Nazi dogs and sheer Nazi numbers? They face a moral dilemma that gives this nail-biter the feel of a parable. What CAN nonviolent people do when confronted with murderous brute force? Can they be as ruthless?

“Green Room” has logic issues, “counting shotgun shells” issues, timeline issues and urgency issues (as in “Shouldn’t we be panicking now?”) .

But even when he slacks off in the suspense department, Saulnier ratchets up the violence — gruesome, bloody, box-cutter wounds and the like. And if you can avoid averting your eyes and keep from slipping off the edge of your seat, you’re going to want to shout suggestions at the cast on the screen.

Doesn’t matter if they can’t hear it.They’re still going to need the help.

MPAA Rating:R for strong brutal graphic violence, gory images, language and some drug content

Cast: Anton Yelchin, Imogen Poots, Alia Shawkat, Patrick Stewart, Eric Edelstein
Credits: Written and directed by Jeremy Saulnier. An A24 release.

Running time: 1:33