Many young actresses take their work too seriously, but not Felicity Jones. A recent starring role in the 18th-century tragedy Luise Miller on London's West End required the 27-year-old Brit to die a terrible death each night, but in one performance she opted to keel over with a big smile on her face. "A cast member dared me to," she explains. "Everyone thinks we're solemn, but there were a lot of jokes going on."

That sense of spontaneity proved useful to Jones, who has been acting since she was 11, in her American big break, Like Crazy, a largely improvised tale of college sweethearts struggling to maintain a transatlantic relationship. "The first few days of shooting were incredibly frightening," she says of the Sundance hit, in theaters this month. "There's no script. But after a few takes, you find the right words."

Director Drake Doremus was so impressed by Jones that he cast her in his next film, a drama about a coquette who tempts her teacher (Guy Pearce). But up first is the comedy Hysteria. "It's about the invention of the vibrator," Jones says with a laugh. "There's a scene in which my character decides to give the machine a go. Doing that in front of the entire crew was . . . interesting." Talk about an actress with buzz.

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