By Kate Ward
Updated October 07, 2011 at 12:50 PM EDT

It’s not often that “the girl you hated in high school” is the heroine of a film. But that’s what Charlize Theron plays in Young Adult, a dark comedy that follows Mavis, a writer who returns to her hometown in an attempt to win back her married high school boyfriend (who just happens to also has a baby on the way). Shopping for a sexy get-up to attract her ex, played by Patrick Wilson, Mavis tells a store employee why she needs to impress: “He’s seen me recently … But his wife hasn’t seen me in awhile.”

If there’s anyone who could turn such a woman into an endearing character, it’s Juno dream team Jason Reitman and Diablo Cody, who are reuniting for this Dec. 9 flick. Watch the trailer after the jump — and then jump for joy seeing that Patton Oswalt’s involved too.

Read more: