By Anna Menta

If you want to watch Charlize Theron jump off cliffs, free-solo climb mountains, and kayak through white-water rapids, then the APEX movie on Netflix is definitely for you. And really, why wouldn’t you want to watch that?

Directed by Icelandic filmmaker Baltasar Kormákur, with a screenplay written by Jeremy Robbins, APEX stars Theron as Sasha, an experienced climber grieving the death of her husband (played by Eric Bana). She embarks on a solo hiking-and-kayaking trip in the Australian wilderness, where she meets a friendly local (Egerton) who offers her travel tips. But when she follows the route he suggests, she quickly realizes he isn’t friendly at all. He’s a deranged serial killer, and he wants to hunt the most dangerous game: her.

Theron, a seasoned action star known for doing her own stunts, leapt off cliffs into pools of water and dangled off the side of a mountain for this movie—which was filmed, for the most part, on location in the Australian wilderness. One of the most jaw-dropping stunts Theron did for APEX served as the movie’s big climax: Sasha, alone, free-solo climbing up a mountain. Theron really was on that actual mountain you see in the scene, albeit with a rope and harness.

“It’s [Charlize], basically with hundreds of meters underneath her,” director Baltasar Kormákur told Decider in a recent interview. “I would almost have to crawl to her to give a direction, because I couldn’t stand there. It was such a dead drop. Her doing that was this a surprise to me, that she would be willing to do that. We could have done it in a different location. But she really wanted to do that. OK, let’s just do it. We found the location, so why not?”

Did Charlize Theron do her own stunts in APEX?

Charlize Theron did some, but not all, of her own stunts in APEX. In an interview for the APEX press notes, Theron was careful to give credit to the stunt women she worked with on the movie, particularly when it came to the white-water kayaking and other dangerous rapid water scenes.

“Anything you see of me going down a waterfall or some of the really dangerous rapids in nature, where we didn’t know if there was a rock underneath, I had two incredible women, River Mutton and Luuka Jones, doing that for me,” Theron explained. “We had world‑class, Olympic‑level kayakers doing a lot of my kayaking. I thought I’d be great at kayaking because I’m so comfortable in the water and I’m a very strong swimmer, but I really struggled with the kayaking, so I was very grateful to them.”

One exception to that is the scene near the beginning of the film, where Theron leaps off a cliff into a pool of water below. In that case, the Oscar-winning insisted on doing the leap herself—and doing it over, and over again.

“She said, ‘I want to do that,’ and I thought, ‘Oh shit, that’s high,'” said director Baltasar Kormákur in an interview for the APEX production notes. “She jumped, and then she wanted to do it again and again: ‘I’ll do it better. You could see the producers’ faces around me: ‘Before anything happens, please stop this.'”

And the climbing scenes were all Theron, both on the real mountain, and on custom-built sets.

“The climbing, though, I think I did all of it, and I loved it,” Theron said in the same press notes interview. “We built a set with two big walls and I just climbed the hell out of it. Balt would just roll, and there’d be three cameras. Our director of photography, Lawrence Sher, was unbelievable, and it became this dance. There was no choreographed ‘action.’ I would just start climbing, not really knowing where I was going, and the cameras would find me. It was the most organic action I’ve ever done.”

As for that final climb on the real mountainside, what you see in the movie took much, much longer in reality.

“To make it look like real climbing, you have to actually climb,” Theron said. “You have to kick all those muscles in or it starts to look fake. What you see takes maybe 20 or 30 seconds in the movie, but it took me about 38 minutes to do. It was that hard.”