Most people wouldn't peg Charlize Theron as a science-fiction actress. The first time she tried her hand at the genre (in the Johnny Depp space-psychodrivel "The Astronaut's Wife"), it failed both critically and commercially. Theron has had better luck - and is far better known - for her heavy, dramatic roles, such as "Monster" and October's sexual-harassment saga "North Country."

Now, with an Academy Award under her belt, Theron returns to sci-fi with a sleek adaptation, "Aeon Flux." She ventures into the genre again with the shadow of her Best Actress predecessor, Halle Berry (and Berry's critically mauled foray into the action genre, "Catwoman") hanging heavily over her head.

Based on the 1995 MTV anime series created by Peter Chung, "Aeon Flux" is the story of a totalitarian society masquerading as a utopia. It follows the one woman (Theron) who can expose the civilization's faults.

Theron wanted Chung to be an integral part of the movie's creation process. "I did meet with Peter, and Peter came onto the set," she said. "This is his baby, so we wanted to keep him involved. I wanted him to be happy (and) to see it like we were being authentic to what he created."

To keep the film true to the original, the filmmakers kept much of its hyperstylized world of anime. Theron felt this accuracy helped her keep the character grounded in the story.

"For me as an actor, all of those elements play such a huge part in the performance that you are able to deliver," she said. "I need those surroundings. I need the wardrobe. I need the hair and makeup. When you work hard enough, you can just let it go and let it be a natural process without manipulating it."

Gone, however, is her character's original costume. "You know, it is a cartoon, and I am not a cartoon, and I cannot run around in a G-string and do the splits because Paramount will not be able to release the film," she said.

To manage the character's signature splits and other moves, Theron had to train extensively and, like her role in "Monster," she changed her appearance for this movie. By learning gymnastics and karate, Theron transformed her body into something more realistic for the character. The process was a welcome change for the actress.

"I wanted to learn how to actually do these things versus just making my body look like I could do them, but I could not," she said. "But at the same time, I learned incredible skills."

In fact, "Aeon Flux" marks the first time Theron has taken on such a physically challenging role. "I mean, I became a gymnast on this film, which was something I had never done before - So that was a huge interest for me was to kind of go and push my body to those limits to actually learn the skills," she said.

"There was a goal at the end of the day, and that was for me to be able to do these things."

Even so, Theron believes the film boils down to the ideas the character represents. "The whole film is really about questioning your government, and I think right now, in this day and age - the majority of America is doing that," she said.

"It deals with issues that I think we are dealing with right now, and if we do not pay attention to them, we will be dealing with the final product of what 'Aeon Flux' deals with 400 years in the future. So maybe we can learn something."