Forget “gritty.” “The Rover” is so rank that if you cut yourself on it, you’d need a tetanus shot. The story takes place “10 years after the collapse,” an undefined apocalypse that swept away virtually every vestige of law but the Darwinian laws of nature. Part road movie, part survival drama, it’s a grungy return to the Outback nihilism of the “Mad Max” movies that put Australian cinema on the world’s radar.

The filmmakers do a solid job of grounding the extreme story in the concrete reality of frontier life. The landscape of “The Rover” is an arid, flyblown sandpit. We see a guarded container car train with Chinese markings clank across the horizon, hinting at mineral riches beyond the reach of the characters. A vastness of tarmac roads connects nasty clusters of buildings that don’t add up to towns. You don’t want to look too closely at what’s hanging from the telephone poles. These are the least welcoming wide open spaces this side of Antarctica.

Guy Pearce and Robert Pattinson, looking like they’ve lived under a bridge for years, play Eric and Rey, a bad-ass nomad and a criminal drifter thrown together by fate when Rey’s brother’s gang steals Eric’s car, leaving the wounded Rey behind. For reasons undisclosed until much later, Eric wants his car back. He is relentless in his pursuit. With Rey as his hostage-cum-partner, the hunt leads to a spaghetti western’s worth of dusty showdowns, squinty standoffs and gut-rupturing gunplay.

The film benefits from the script’s laconic dialogue. Asked to explain himself, Eric says, “I was a farmer. Now I’m here.” Bringing the rather simpleminded Rey up to speed on his situation, he explains, “Your brother left you to die. It’s what people do.”

Pearce’s powerful, hollowed-out performance only hints at what might be rattling around inside this man’s ribcage, about to burst out. It’s absolutely the correct choice. If you want to understand him, look at his filthy button-down shirt and khaki shorts, and imagine him back when there were weekends. Now he’s a man for whom hell will hold no surprises.

Rey is too dim to be haunted by his past. He’s a born sidekick, an ignorant buffoon whose sometimes fatal eruptions echo the acting out of an attention-seeking child. We know he hasn’t got a bright future, and we equally know he doesn’t deserve one, but we can’t help hoping he makes it.

Pattinson, with his asylum-escapee haircut and rotted teeth, jabs a grimy finger in the eye of every “Twilight” fangirl. His performance is wildly mannered, full of twitching, tic-riddled shtick, but he gives the makeover his total commitment. Rey and Eric’s lack of trust in each other is a hurdle as big as any of the physical hardships along their way.

Director David Michôd gives us long, austere periods of rising anxiety as the camera tracks our antiheroes across the killing grounds, squeezing tension out of all the empty space around them.

The slightly overlong film wanders a bit at the end. I’m not sure how serious Michôd is about his climax. I take the last moments of this dystopian film as the kicker to a shaggy-dog story, tilting the don’t-mess-with-me revenge saga in a weirdly comic way. It reveals Eric as a survivor willing to risk his life for — well, let’s just say it was right there in the title all the time.