This far into his screen career, it shouldn’t be a revelation to anyone that Zac Efron can act. He’s shown canny comic chops in the “Neighbors” films, wounded all-American ennui in “We Are Your Friends” and “At Any Price,” even a credible against-type chill as Ted Bundy in “Extremely Wicked, Shockingly Evil and Vile” — none of which has been enough to overtake his bland, floppy-banged, career-minting “High School Musical” persona in the popular imagination.

In “Gold,” an otherwise ordinary survival thriller from actor-director Anthony Hayes, Efron resorts to the same kind of extreme measures that fellow heartthrob Ryan Reynolds took to prove his worth in “Buried”: headlining a one-location genre piece so leanly conceived that it has scarcely anything to showcase but his commitment and grit. As a lone drifter guarding a precious quarry in deadly desert conditions in a faintly futuristic nowhereland, he’s good, as anyone’s who been paying attention should expect. Beyond that, it’s a somewhat arid exercise.

A well-regarded character player in his native Australia, Hayes had a supporting role in David Michôd’s brooding, post-apocalyptic mood piece “The Rover” — which, coincidentally or otherwise, casts rather a long stylistic shadow over Hayes’ second feature as a director. As in that similarly solemn, nihilistic film, the Australian outback serves as a backdrop for a vaguely defined but emphatically desolate near-future, where human survivors seemingly live off a land that has nothing left to give. In this case, however, the geography is blurrier still: It’s not at all clear where this burnt-out purgatory is, but a blend of American, Australian and Irish accents voice the scant dialogue.

All we need to know, as Hayes and co-writer Polly Smyth drop us into the story with little preamble, is that it’s a place to be escaped, and wherever you’re going, it’s probably not far enough. We’re tersely told that Efron’s nameless protagonist is “from out west”; having clearly been through the wars, he arrives by train at a dead-end desert junction, seeking a ride to a distant “compound” where he’s been promised employment. One suspects it’s not exactly paradise either. Another surly man with no name (played by Hayes himself) agrees to take him, cuing the least chatty road trip imaginable: In this world, even nominal allies are enemies.

When their truck naturally breaks down in the flattest, driest, most forbidding stretch of this highway to hell, all is lost, until it suddenly isn’t. There, glinting amid the sand and stone, is a flash of gold that turns out, on closer inspection, to be a potentially life-changing windfall — if they could only find a way to get it out of the desert and to some manner of civilization. The revived truck’s towrope is no match for this haul, and while the driver knows where to get an excavator, it’s a long journey back. Someone has to stay at this pitiless resting spot, preyed on by wild dogs and a relentless sun, to guard the gold. Such is the setup to finally get Efron alone in the spartan wilderness, battling the elements and his fraying sanity as days turn to eons — marked only by the increasing extremity of the prosthetic makeup work and the shifting palette of Ross Giardina’s grimly handsome lensing, with its veritable biosphere of atmospherically bleached beiges.

The battle, unfortunately, goes precisely as you’d expect at every turn, as Hayes and Smyth’s screenplay itself runs out of gas about halfway through. Sunstroke, dust storms and a malevolently prying nomad (a suitably eerie Susie Porter) all show up on cue, conspiring to make Efron’s abandoned hero lose both his bearings and his mind, but even at 96 minutes, the film feels underplotted and overwrought. It’s hard to care much for a character whose own identity and desires are so opaque to us, and perhaps even to him, which makes “Gold” an odd endurance test for its audience and star alike. Efron, at least, passes it with distinction, his genuinely agonized body language and increasingly unraveled, boyish demeanor eliciting a kind of visceral empathy that spans actor and character alike.

What reward we get from all this is debatable, as the film bloodily staggers to a glum psychological conclusion telegraphed long before the closing credits underline it to the tune of Nick Cave’s mordant “People Ain’t No Good.” Efron’s efforts, meanwhile, will hopefully be met with fuller, livelier showcases for his maturing gifts.