In Atonement, Saoirse Ronan coolly, purposefully destroys her sister's life by accusing her lover of a rape he never committed.
She's quite convincing, and the Irish actress, 13, has learned that being Briony has its own repercussions.
When folks meet her for the first time, says Ronan (whose first name is pronounced SEER-shah), "they're surprised that I'm nothing like Briony. They're so surprised, No. 1, that I have this weird, alien accent and that I'm shaking their hand and smiling. I'm Irish, so I'm messing all the time. Which means, I'm having a laugh. I'm always making jokes. I'm completely the opposite of Briony, basically, except we both have that imaginative thing going on."