In Fiji, there lives a hermaphroditic flatworm, the smirkingly named Pseudobiceros hancockanus, famous for "penis fencing" — an hourlong battle in which two worms wave their dicks to see who wins nature's prize: the right to spawn. If the flatworms crawled to a theater to watch Ben Wheatley's testosterone spree Free Fire, they'd think, Eh, mankind ain't more advanced.

The nine crooks in this 1970s-set shoot-'em-up are also jockeying to mate, or at least date, gun broker Justine (Brie Larson), who's arranging a deal to sell rifles to the IRA. Her buyers, Irish rebels Chris (Cillian Murphy) and Frank (Michael Smiley), and the sellers, a motley crew that includes a failed Black Panther (Babou Ceesay), a twit (Sharlto Copley), and a wannabe James Bond (Armie Hammer), have assembled in an abandoned warehouse with their idiot goons, a suitcase of cash, and a van of AR-70s. But there can only be one alpha, and when the war for respect goes awry — and it does so spectacularly and stupidly in one minute — they're all reduced to bullet-riddled animals who'd still rather shoot each other than survive. These fools spend an hour of the film writhing on their bellies in the dirt. Pair Free Fire with Wheatley's last film, High-Rise, in which Tom Hiddleston's luxury apartment tower devolved into violent, orgiastic chaos, and the director's worldview is clear: Our species belongs in a zoo.

High-Rise brought down the rich. (It's worth watching mainly for Sienna Miller's vamp, who ruins mens' lives while wearing dresses slashed to her navel.) Free Fire ferments testosterone into hooch. The guys are drunk on their own egos, and the film feels like Reservoir Dogs with a hangover. Wheatley swaps out Tarantino's cool suits for disco lapels, and lets cowriter Amy Jump give the men zingers that clang like cheap pots. Copley's Vernon, a prematurely diagnosed child genius, has even given himself a catchphrase. "Vern and learn, baby!" he bleats. Later, Vernon boasts that he's wonderful to women. Justine rolls her eyes. He's oblivious.

Copley and Larson have terrific misfit chemistry. The more he howls — picture a baby pounding his fists on the fridge — the cooler she gets. Unlike the men, Justine will tolerate insults, and even pretend to thaw when Vernon gets his skull cracked on a car door. She knows that the more she coos over him, the more he'll pretend his head doesn't hurt. This is the battle of the sexes, and she's the only one who knows how to play. Yet, at the end of the day, she's a criminal, not a feminist hero, and the more Wheatley and Jump conflate the two — overreaching so far as to position her as the Joan of Arc of gunrunners — the more we sour on her, too.

Once the dudes start shooting, Free Fire becomes a noisy mess. Wheatley has no sense of the building's geography. We can't tell where they're crawling to or who they're trying to kill. Worse, his camera is close-up and spastic. Despite their loud jackets, the nine weirdos become a blur, including known faces like Sam Riley as a whiny junkie and Jack Reynor, bearish beneath a fedora and beard. The editing is so sloppy that Wheatley will keep the lens on one while an offscreen second screams the name of a third, all of them out-clattered by the pop-pop-pop-scream-pop-pop-pop of a roomful of lousy shots. No wonder someone yelps, "I forget whose side I'm on!" I'd tell him, but even after seeing the film twice, I'm not sure who he was.

Confusion could be Wheatley's point. Even they don't seem sure why they started blitzing, or what it'll take to stop. Honestly, neither does the movie. It's absurd and bleak and scrambled in its own intentions. Wheatley doesn't delight in the gore. He explodes more dust clouds than squibs. Usually, I'd prefer a director who didn't gawk at a wound, but if we're meant to feel sickened by idiocy, eventually these bullets need to hurt. I found myself surprised not just by who died, but by how little it mattered — a waste of a death in a film that's literally about wasted lives. Instead, for as fun and loud and popcorny as Free Fire plays to a crowd, I left feeling like Wheatley had missed his own target. He's shown us how low men can go. Then he squashed the worms and skittered away.