Navigating director Jeremy Saulnier’s punk-rock siege horror-thriller “Green Room” is a lot like an NPR Classical listener finding an appreciation for hardcore.

This image released by A24 Films shows Patrick Stewarrt in a scene from, "Green Room." (Scott Green/A24 via AP)

It’s loud, it’s violent and it’s not at all easy — but with the right set of ears and eyes, it’s incredibly rewarding once you drill down to the message.

Yes, Virginia, this gritty tale of nihilistic punks trapped against their will by skinhead club owner Darcy (Patrick Stewart) looks and smells like chum for genre fans champing for early Tarantino or Eli Roth. But it’s a lot more than that.

The plot is very straightforward: The Ain’t Rights — a D.C. band siphoning gas to get home from the Pacific Northwest — sees something they shouldn’t backstage at a club filled with neo-Nazis and end up fighting for their lives to escape.

But what’s intriguing about “Green Room” is the philosophical battle royale playing out under the surface. The seemingly nihilistic punk rockers insist on bringing in the authorities; whatever “-ism” they are pushing with their music suddenly means a lot less than an officer’s response time. Meanwhile, the neo-Nazi club staff are confident enough they’ll game the system to cover up their own misdeeds.

Unfortunately for everyone, the law doesn’t really prevail or even seem to apply after the club’s been emptied and it’s just punks vs. neo-Nazis. Who has guns and in what supply becomes the rule of the day — until Saulnier reminds us that attack dogs and box cutters can be just as deadly.

Anton Yelchin and Alia Shawkat play two of the rockers who seem poised to survive the longest, while Imogen Poots is tremendously intriguing as a wild-card member of another band who ends up trapped with the Ain’t Rights, her allegiance in question for a good chunk of the running time.

But the best nuance comes from Stewart as the boss and Macon Blair (“Blue Ruin”) as one of the club’s managers. The calm, business-as-usual ways in which they set plans in motion to dispose of bodies and prepare for “mopping up” afterward is subtly disturbing in ways that no quick shot of hacked limbs or a shotgun blast to the face could be.

At its absolute core, “Green Room” is about the obsession with being true to a culture. Saulnier’s obviously showing some love for the punk/hardcore scene of his youth with this setting, nailing the tone of being broke and unsuccessful and loving it until you hate it. It’s a culture that’s not all too different than American gun culture, with warring factions within it just like punk rock, or even the culture of a supremacist group. The concept of purity — be it racial, ideological or musical — motivates these characters, triggering learned aggressions to ghastly ends.

If you consider how quickly culture takes a backseat to survival, “Green Room” is a brilliant critique of the nearly instantaneous politicization of gun violence in America on all ideological fronts. That it plays just as easily as a visceral, “OMG, did you see that?” survival horror with a suspense thriller twist is a testament to Saulnier’s ability to operate at multiple levels at once.

Saulnier’s last film “Blue Ruin” explored similarly violent territory, but with an intense focus on one man’s revenge plot gone haywire. “Green Room” lacks the character development of his last film, but it makes up for it in the masterful ways it is both startling and thematically deep.

“Green Room” is rated R. One hour, 35 minutes. Four stars out of five.