** SPOILERS **
Traveling around the country cramped in a crappy Scooby Doo van, siphoning off gas from other cars because you have no money, putting on gigs in an empty pizza parlor for six bucks a head... being part of an unsigned punk rock band kinda sucks enough -- details Green Room captures persuasively -- and that's before they unwittingly witness a gruesome murder in a dingy Pacific Northwest club owned by neo-Nazi white supremacists. This is what happens to the members of the band The Ain't Rights (billed incorrectly as The Aren't Rights), played by Anton Yelchin (Like Crazy), Alia Shawkat (Arrested Development), Joe Cole, and Callum Turner. They just showed up to play a gig for $350 (delightfully opening with "a cover song" aimed right at pissing off the neo-Nazis in the audience), but when Yelchin returns to the green room to retrieve Shawkat's iPhone, he finds a fresh corpse of a girl with a knife in her head The Walking Dead-style, her friend Imogen Poots in hysterics, and a bunch of huge neo-Nazis standing around looking guilty. Because they did it. Next thing you know, Yelchin and his band mates are trapped in the green room, barricading themselves in, as things get much, much worse for them and everyone involved.
The arrival of the police is quickly neutralized by the arrival of the club's owner and the leader of this neo-Nazi cadre, Sir Patrick Stewart, playing against his beloved type as a menacing schemer more than willing to let young bodies be hacked by machetes and mauled by dogs to address the growing problem in his club's green room. Most of Green Room takes place within the green room, as the band and Poots attempt to weigh their shrinking options and rally some form of escape. Yelchin's left arm is an early casualty, gruesomely hacked up by Stewarts' men so that his hand is nearly severed from his wrist. Thank God for duct tape (a sentiment Matt Damon echoes in The Martian). Green Room relentlessly ratchets up the brutality as the band and Poots make repeated attempts to escape the club, only to find rabid dogs and shotguns and more machetes waiting for them, so that fewer and fewer of them are able to return to the relative safety of the green room to lick their wounds.
Writer-director Jeremy Saulnier maintains a harrowing and merciless edge to the proceedings, with the question of which band would be each character's "desert island band" as the lone source of welcome comedy occasionally diffusing the tension. (The shout out to Prince could not have been more timely or welcome.) Yelchin, who plays Mr. Chekov in J.J. Abrams' Star Trek movies, confronting Stewart, whom everyone in the Alpha Quadrant reveres as Captain Jean-Luc Picard of Star Trek: The Next Generation, late in Green Room plays like some kind of bizarre but thrilling Star Trek mirror universe episode or fan fiction. In the end, the bloody and remorseless Green Room leaves us with one less punk rock band in the world, but also a lot fewer evil skinhead a-holes in the world, and ultimately, it seems a fair trade.