Keira Knightley Just Wanted To 'Have Some Fun' With 'Jack Ryan'

Though she got her break in a movie about pirates fighting other ghost pirates, Keira Knightley has made a career of picking challenging roles in sophisticated movies. But with all due respect to Mr. Tom Clancy and Sir Kenneth Branagh, what's the deal with "Jack Ryan"?

As MTV News' Josh Horowitz found out during his recent talk with the actress, she always goes for the difficult roles, but Knightley also occasionally just wants to have some fun.

"I definitely went for the characters that I found the most challenging and the strangest and often people that if I met them I wouldn't necessarily like them and to try and understand what makes the other person tick is what I really, really enjoy about my job," said Knightley. "Saying that, I did get to the end of "Anna Karenina" and go, "I just need to do something a bit fun."

Sometimes a girl just wants to have a little old-fashioned Hollywood fun. "So the 'Jack Ryan' of it and 'Can a Song Save Your Life?,' which I did before, are more in the realms of entertainment," Knightely said. "'Jack Ryan' is a thriller, but it's a good old-fashioned Hollywood thriller, where people run around and things explode. I don't really run around and nothing explodes around me, but ..."

Does she explode?

"I don't explode either—wow—although that could be interesting," she said. "Who knows? I haven't finished yet"

"Jack Ryan" opens on December 25, 2013.