Anyone who has seen Charlize Theron kick butts onscreen knows she has the tough athleticism to handle herself in the most punishing action roles. Whether with firearms and blades, fists and feet or behind the wheel, her work is made more visceral by the insistence on doing her own stunts whenever possible. In films like Mad Max: Fury Road, Atomic Blonde and The Old Guard, her physicality is the equal of any male co-star. Netflix’s bracingly nasty action-thriller Apex is a fine addition, plonking the star down in a rugged Australian landscape and throwing nature’s formidable might at her while stirring a psychotic serial killer into the mix.

After the departure of 2024’s Touch, an elegant, decades-spanning drama of lost love, Icelandic director Baltasar Kormákur is back in his more customary intense survival mode with this sinewy story of an extreme adventure addict for whom testing her limits is a vocation, even more so once the odds are stacked against her. The taut nail-biter is well-acted, crafted with skill and briskly paced, running a tight 95 minutes. It’s the rare breed of streaming original that can safely be called a real movie.

Theron plays Sasha, an American first seen making a challenging winter ascent up a sheer cliff face of Norway’s Troll Wall with her Australian boyfriend and regular extreme sports partner, Tommy (Eric Bana). Right from the start, Kormákur and ace DP Lawrence Sher give us a nerve-rattling sense of the danger they tackle with the kind of vertiginous drone shots that will be effectively used throughout.

Even as a storm is closing in, Sasha wants to keep moving upwards with bandaged, bleeding fingers while Tommy sensibly suggests they call it a day. He eventually convinces her after a minor slip and they pitch their portaledge vertical tent, which looks like a fragile paper lantern when suspended on the cliff wall for the night. 

Tommy tells her he has reached his threshold with these extreme trips and wants to stop, also expressing concern that Sasha tends to rush at challenges, taking too many chances. It’s not entirely surprising that this ends in tragedy the next day as they attempt a descent to safety.

Cut (via stylish main title graphics) to Australia, where the grieving Sasha has gone looking for solitude on a camping trip. At the fictitious Wandarra National Park, she registers her name with the ranger (Aaron Pederson), who cautions her against venturing into the isolated area alone. His concerns clearly have something to do with the office wall covered in “missing persons” handbills.

Screenwriter Jeremy Robbins sets up what appears to be a potential threat in a creepy kangaroo hunter (Matt Whelan) and his drunken mate (Rob Carlton), whose names alone, Diesel and Ripper, carry a hint of menace. Their lascivious flirting at a backroads supply store makes Sasha bristle as she brushes them off. 

The more benign-seeming presence is fresh-faced, friendly local boy Ben (Taron Egerton, pulling off an impressive Oz accent), who sells his home-made beef jerky at the store. At the gas pump, he offers help with directions, advising her to skip the straight line and take a more scenic route to her destination. He’s not lying; the views are spectacular.

The hunters turn up that night at her camping site overlooking a steep gorge and river, their van loaded with bleeding roo carcasses. Sasha quietly freaks out as they become more aggressive, but they get bored and move on once she locks herself in her jeep. 

The next morning, she scrambles down to the river for some white-water kayaking, which takes on hair-raising shades of The River Wild (remember action-Meryl?) once she’s being pursued through an obstacle course of boulders and waterfalls. The fun starts when Ben turns up soon after her pack is stolen and insists on offering her replacement gear and breakfast at his out-of-the-way campsite. But her host soon reveals other plans, giving her a short head start before hunting her down with a crossbow.

Apex joins a long line of thrillers — from Wolf Creek and Killing Ground all the way back to 1971’s Wake in Fright — that are not exactly enticing tourism commercials for a chill time in off-the-beaten-track Australia. Kormákur takes full advantage of the country’s dramatic landscapes and dense bushlands, the latter making ideal terrain for Sasha’s initial flight, a pulse-racing sequence that has her sprinting through the trees like a blur.

Egerton makes Ben a suitably chilling figure, balancing rough-edged charm with off-putting humor, cunning with lapses of boyishness, signs of psychological damage with matter-of-fact sadism. The stakes are dialed way up once he catches his prey and drags her to his gruesome hideout, where Sasha gets a more complete picture of the nightmare in which she’s stuck. 

Things get gnarly when Ben shows off his nifty dental work and reveals why it’s best to decline the tasty jerky. But those moments that flirt with horror are less exciting than the constant switches in who has the upper hand. Theron’s Sasha is no invulnerable hardbody but a legitimately terrified and battered captive, so it’s a thrill whenever she seizes a momentary opportunity to turn the tables. Her rock-climbing skills also come in handy when she’s trapped in a narrow gorge, and soon after when a hairy ascent provides echoes of the prologue.

Most people’s money would be on a Theron character in any life-threatening situation, but Egerton’s Ben puts her through her paces with vicious determination. All of this gets a steady electrical charge from Kormákur’s muscular direction, Sher’s sweeping camerawork and a no-nonsense, ominous score by Högni Egilsson. 

The one head-scratching choice is the jarring end credits song, “Nasty Boy,” by Icelandic electropop band Trabant, completely at odds with the tone of the closing scenes. This might be one time when Netflix’s credit-crushing auto-play jump to other content is a blessing.