Until recently, Mia Thermopolis was an ordinary schoolgirl, now she is the heir to the throne of the small European state of Genovia. Granny, the Princess Dowager who teaches Mia royal etiquette, arranges for her to be interviewed on America's most popular program. But the interview turns into a disaster: Mia laughs at the teachers of her own school, reveals her mother’s secret and quarrels with her friends - and all this to an audience of millions...