United Kingdom, April 25 -- Taron Edgerton "discovered" he is afraid of heights - while scaling a mountain for a scene in Apex.

The 36-year-old actor stars with Charlize Theron in the new action thriller, which is set in the Australian wilderness, and while the actress was committed and enthusiastic about doing her own stunts, Taron found it a more daunting prospect.

Charlize told People magazine: "The climb that we have to do together was really, really hard, especially for Taron because he had a ... I don't want to give anything away, but it's a challenging climb for us.

"And we spent a lot of time on that wall, kind of stuck to it. That was so impressive to watch him problem solve how to get his body up this mountain. I was like, 'I...