Mia Thermopolis (Anne Hathaway) is the average teenager - sweet, a little geeky, and pretty much invisible to everyone with the exception of her mother, best friend Lilly (Heather Matarazzo) and Lilly's older brother Michael (Robert Schwartzman). Making it through high school without throwing up is a challenge in itself for Mia, so it doesn't come as welcome news when her estranged grandmother, Queen Clarisse Renaldi (Dame Julie Andrews), shows up out of the blue and calmly informs her that she is in fact the heir to the throne of a European country called Genovia. Suddenly Mia's life is thrown into complete overload. She's being taught about scarves, waves, and pears in order to become a perfect Princess, she gets a makeover and a tough looking, yet sweet bodyguard and limo driver called Joe (Hector Elizondo). Things get out of hand when the media gets a hold of the story and suddenly Mia is thrust into the spotlight in the newspapers and in school. On top of all of that, Mia has a choice to make. She must decide by Genovia's Independence Day Ball whether she longs to relinquish her claim on the throne or to become the Princess and heir to the throne her father, Philippe Renaldi (Rene Auberjonois), and grandmother want her to be.

Now settled in Genovia, Princess Mia faces a new revelation: she is being primed for an arranged marriage to an English suitor.

The sequel is filled with 'Cheetah-style' adventure, drama and humor. The escapade begins when Galleria enters the group in a Barcelona music festival, and the spirited foursome (escorted by Galleria's protective mom Dorothea and Chanel's mother Juanita) embarks on a journey of a lifetime. But things get way more complicated once the four best friends arrive in España: they meet Marisol, a talented solo singer and her manager/mother Lola, who unknown to the Cheetahs, may lead their group to break up; they are shown the sights by Joaquin, a handsome young tango dancer who falls for Dorinda; the fashion bug bites aspiring designer Aquanette; Chanel questions the future of her mother and Luc's relationship; Galleria begins to lose faith in the Cheetah Credo; and the Cheetahs' dream of becoming stars may be dashed forever when they are informed they've broken a stringent festival rule.