Mouse Depero (voiced by Matthew Broderick) has been sickly since childhood, but has two huge ears. He spent his childhood in the library, and slowly began to learn to read and write. He likes the stories of heroes saving beauties in fairy tales, and often fantasizes that he can become a brave knight and help beauties when they are in trouble. During an outing, Depero met the Princess and the Pea (voiced by Emma Watson). Depero, who longs to be a hero, was expelled by his father Lester (voiced by William H. Macy) because he violated the strict laws of the Mouse Kingdom. In the vast land outside the Kingdom of Dor, Depero met the mouse Roscuro (voiced by Dustin Hoffman), who was also expelled from his own country. Soon after, the exiled Depero learned that the Princess and the Pea was imprisoned in a dungeon. Depero, who loved the princess, decided to fight to the death to rescue the princess. Will he defeat the evil and win the love and dignity he deserves? This film is adapted from the novel of the same name by Kate DiCamillo, a famous American children's writer.