With his new Netflix film “Apex”, director Baltasar Kormákur continues an eclectic run of films that has featured everything including wild genre concoctions, gritty thrillers, buddy action-comedies, and awards-caliber dramas. “Apex” definitely falls in the ‘genre concoction’ category. Kormákur has made a propulsive survival action thriller that even dips its toes into horror when you’re least expecting it.

Working from a kinetic original screenplay by Jeremy Robbins, Kormákur takes an action-fueled approach to exploring grief and guilt, with lead Charlize Theron (who also produces) carrying much of the load. She plays an adrenaline junkie named Sasha whose life is turned upside down after losing her partner Tommy (briefly but wonderfully played by the ever underrated Eric Bana) in a rock-climbing tragedy.

While its script and its star are vital pieces, just as crucial are the eye-popping visuals. The film was shot on location near Australia’s Royal National Park and along the gorgeous Blue Mountains in New South Wales. Canyons, caves, tall peaks, raging rivers, and dense forests provide the film with a stunning yet unforgiving natural setting. The rest is handled by the crack visual effects teams from Kormákur’s previous outdoor thrillers, “Everest” and “Beast”. They use the beauty of nature as both the centerpiece and the backdrop for some thrilling action sequences.

Five months after Tommy’s death, Sasha is on the road in scenic southwest Australia, living alone out of her van and still mourning her loss. She swings into a rural gas station to grab some supplies where she’s harassed by a meat-headed hunter. But she’s helped by a seemingly friendly local named Ben (Taron Egerton) who even recommends some area sightseeing and a good camping spot at a nearby river.

But Sasha’s efforts to find solace in solitude are quickly thwarted when she once again encounters Ben. This time it’s deep in the wilderness, and Ben is no longer the kindly and helpful guy from before. Instead, he reveals himself to be a sadistic psychopath who has lured Sasha into an arena where he’s the hunter and she’s his prey. But Sasha is far from weak and defenseless. And despite being isolated in a treacherous environment, her grit and resourcefulness makes her more than Ben bargained for.

While the story is simple and straightforward, it does its job in defining the stakes, building tension, and propelling us from one harrowing action scene to another. But just as you think you have a good read of the movie’s pulse, Kormákur and Robbins throw us a grisly second-half curveball that manages to be both deeply unsettling and (in its own delightfully deranged way) darkly amusing. It’s a devilishly macabre twist that raises a few obvious yet overlooked questions. But odds are you’ll be having too much fun to care.

“Apex” is an impressive two-hander that gets go-for-broke commitments from its two stars. Egerton has a field day playing the maniacal Ben, squeezing out every drop of depravity he can without turning the character into a caricature. Meanwhile, I’m not sure Theron has ever been this gutsy and determined. She pours all of herself into a demanding role, finding moments of emotional truth among the intense physicality. Together with the stunning vistas, exhilarating camerawork, and white-knuckle tension, Theron and Egerton turn a simple survival story into a riveting action thriller that never lets you out of its grip.