When Princess Rosalina (Lovato) is threatened by an evil dictator bent on taking control of her country, she is whisked away and placed into the Princess Protection Program, a secret agency that watches over imperiled princesses around the world.

Mason, an agent with the program, hides Princess Rosalina in his own home where, with the help of his daughter Carter (Gomez), she adopts the cover of an ordinary teen named Rosie. An insecure tomboy, Carter works at a local bait shop after school and dreams of going to the school dance with her crush, Donny, the school hunk.

Rosie quickly becomes popular at school which Carter must learn to accept but the two also form a close bond as Carter helps Rosie transform into a normal teenager and Rosie shows Carter how to find the princess within herself.