15-year-old high school student Mia (Anne Hathaway) lives in the United States with her mother, but she is very insecure and is often laughed at by her classmates. On her 16th birthday, she meets her grandmother (Julie Andrew) and discovers that this elegant lady is the queen of the small European country of Genovia, and Mia is the princess of this country. At first, Mia was very reluctant, but only after her mother's mediation did Mia's attitude soften. In order to successfully inherit the throne, the Queen had to make a series of changes to her granddaughter, which troubled Mia, who usually lived an informal life, and even had conflicts with her good friends. Mia's identity was exposed by a good classmate, and she suddenly received great attention from the media. Everything suddenly made Mia want to escape everything. Fortunately, in her father's diary, she regained her confidence. Mia became a princess and found the love she wanted.