"One of them is lying. So is the other."
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. Andie Anderson covers the "How To" beat for "Composure" magazine and is assigned to write an article on "How to Lose a Guy in 10 days." They meet in a bar shortly after the bet is made.