Princess Mia (Anne Hathaway) returns to Genovia after graduating from college. The princess's arrival caused a sensation across the country, and Mia was very excited about it. However, at a royal hearing, the Lord Chancellor announced that the princess must marry to inherit the throne. Mia must be engaged within 30 days or she will have to relinquish the throne. The Queen (Julie Andrew) and her assistants hurriedly help Mia choose a husband. After several choices, Mia finally got engaged to a young and handsome aristocratic man. The young boy Nicholas (Chris Pine), who competes with her for the throne, has an unspeakable affection for Mia. The boy's uncle wants Nicholas to seduce Mia and make her unable to get married within a month. However, a real affection develops between the two young people.