What happens when two people with different ideas about love find it with each other? Tom Hansen (Joseph Gordon-Leavitt) is a dreamy-eyed romantic who's been burned in the past. Summer Finn (Zoey Deschanel) has never had a problem getting a man, but she doesn't always want one. The word commitment-phobe doesn't even sum it up -- she doesn't believe in love and isn't really looking for it. But when the two meet at work, a greeting card company where cheesy pronouncements about the L-word are thrown about constantly, all bets are off. The 500 days they are together -- first as friends, then as flirts and then as a couple -- hold different meanings for both of them, and it takes a long look back at their rocky relationship to see if their dueling definitions of love can be reconciled.