Benjamin Barry is an advertising executive and ladies' man who, to win a big campaign, bets that he can make a woman fall in love with him in 10 days.
When her brother decides to ditch for a couple weeks in London, Viola heads over to his elite boarding school, disguises herself as him, and proceeds to fall for one of her soccer teammates.
Little does she realize she's not the only one with romantic troubles, as she, as he, gets in the middle of a series of intermingled love affairs.
Beca, a freshman at Barden University, is cajoled into joining The Bellas, her school's all-girls singing group. She wants to join the boys team, but they do not allow girls. Unfortunately, she didn't plan falling in love with her roommate Duke. What makes matters worse is that Olivia starts to fall for Sebastian because he/she has a sensitive side.
Injecting some much needed energy into their repertoire, The Bellas take on their male rivals in a campus competition. If things couldn't get more problematic, the real Sebastian (who was in London working on his music) comes home early.
He arrives on campus and has no clue that he was replaced by his twin sister. Duke wants Olivia who likes Sebastian who is really Viola whose brother is dating Monique so she hates Olivia who's with Duke to make Sebastian jealous who is really Viola who's crushing on Duke who thinks she's a guy...