Felicity Jones has revealed more information about her "Rogue One: A Star Wars Story" character following the release of the new trailer on Thursday during the Olympics.

Jones plays Jyn Erso, the central protagonist of the film, who is recruited by her scientist father (played by Mads Mikkelsen) to join a team that sets out to steal the plans for the Death Star.

“She is absolutely a very unlikely heroine,” Jones told Entertainment Weekly. “She’s someone on the edges and fringes of society. Physically, she’s smaller than everyone else around her, but...when someone has something they believe in, that’s what powers them, that’s what motivates them, that’s what can give someone enormous strength.”

Jones emphasized that training to play a badass wasn't so easy. “I’m laughing now, but at the time, it was physically exhausting,” Jones said. “It took a lot of hours of practice, and I worked with a kung fu coach, and I learned to fight, even though I never thought beating up Stormtroopers was something I’d be doing in my job. It came through hard work and lots of practice and rehearsals.”

Director Gareth Edwards noted that he cast Jones for the part not just because of her fighting ability, but also because of her vulnerability.

"There were a lot of people who could learn how to fight and beat people up and do the physical side of it," Edwards said. "For me, the most interesting thing is when there’s a crack in the armor, when you can glimpse the vulnerability in someone. You can just hang the camera on Felicity and not say a word, and you can feel her having a million different thoughts. You get interested in what she’s thinking and what’s going on. She can be very observant within a scene. It doesn’t always have to be about her directly, but we’re experiencing it through her. She just has that knack for pulling you in."

For more on Jones' casting and the role, plus exclusive photos, head over to EW.

Directed by Edwards, written by Chris Weitz and Tony Gilroy, based on a story by John Knoll and Gary Whitta, and starring Jones, Diego Luna, Ben Mendelsohn, Donnie Yen, Mads Mikkelsen, Alan Tudyk, Jiang Wen and Forest Whitaker and many others, "Rogue One: A Star Wars Story" hits theaters on December 16, 2016.