After getting over the revelation that she is a princess and part of the royal family of the small and obscure European nation of Genovia (with a population of just 50,000), American teenager Mia (Hathaway) moves to the actual country she represents, with her best friend, Lilly (Matarazzo) tagging along during summer vacation.

As she learns the job of being a country's future ruler, one challenge she's faced with is the prospect of being set up in an arranged marriage.