Like the book, the film follows a brave young mouse named Despereaux (voiced by Matthew Broderick), who meets and eventually saves the young human Princess Pea (Emma Watson) from a plot by the exiled rat Roscuro (Dustin Hoffman) and the leader of the rats, Botticelli (Ciarán Hinds).
The voice cast also includes Tracey Ullman as Miggery "Mig" Sow the servant girl, Robbie Coltrane as Gregory the jailer, William H. Macy, Tony Hale, and Frances Conroy as Despereaux's family, Kevin Kline as Chef Andre, and Frank Langella as the mayor.
This film provides examples of:
- Abled in the Adaptation: In the book, Miggery had gone partially deaf from all the times her abusive "uncle" slapped her on the ears. In this film she can hear just fine.
- Adapted Out: In the novel, Despereaux was mentioned to have a sister, Merlot, but she doesn’t make an appearance in the film.
- Blind Seer: After Despereaux is exiled for the crime of consorting with humans, he meets the blind mouse Hovil, whose eyes are pearly white. Hovil is charged, among other tasks, with overseeing the gateway into the darkened sewers beneath the dungeon. Early on, he is the only mouse who seems sympathetic to Despereaux's curiosity and fearlessness. It appears to the viewer that Hovis lowers criminals into the sewers using a thread whose color corresponds to their crime. For Despereaux, convicted of courage, the thread is red.Despereaux: Red?
Hovil: Ah, so they tell me. You're the brave one?
Despereaux: I guess.
Hovil: Wear it proudly. There's no shame. - Bratty Food Demand: The leader of the boorish dungeon rats demonstrates his authority to Roscuro by showing him a large group of rats surrounding a large pile of food and chanting, "Eat! Eat!" but not daring to eat until the leader has rung the gong.
- The Chain of Harm: Mentioned in the ending narration:Narrator: So, you could call all of this a big misunderstanding if you wanted to. A king was hurt, so he hurt a rat. And a rat was hurt, so he hurt a princess. And a princess was hurt, so she hurt a servant girl without even meaning to do it. And that servant had been hurting for so long, that almost nothing could make her feel better. But was it a mistake, or was it just good luck? Because the servant girl went back to her farm. And the jailer finally found his princess. And the king found something stronger than grief. And the mice finally got rid of their fear. And the people of Dor lived side-by-side with their rats...all except one, who went back to sea and felt a cool breeze each morning, and the sun on his face every afternoon. And we'd tell you that they all lived Happily Ever After, but...what fun is that?
- Composite Character: Gregory is a composite of the jailer from the book and Mig's father.
- Distinguishing Mark: Mig has a heart-shaped birthmark on the back of her neck. When her father sees it, he realizes that she is his daughter who he gave up as a baby because he couldn't take care of her, all those years ago.
- Does This Remind You of Anything?: See Nightmare Fetishist, below.
- Faceplanting into Food: A rare Played for Drama example. When the queen witnesses Roscuro coming out of her bowl of soup, the resulting shock causes her to die on the spot and she faceplants right into her soup.
- Family-Unfriendly Death: The Queen. It's unclear if she suffered a fatal heart attack, or drowned in her soup after fainting and faceplanting in it, but neither option is pleasant.
- Fisher King: The kingdom goes grey and overcast when the King goes into mourning.
- Fully-Dressed Cartoon Animal: Despereaux, Roscuro and other mouse and rat characters, unlike their book counterparts, who are drawn nude.
- Happily Ever After: Subverted. The narrator remarks that this is normally where everyone lives happily ever after in the epilogue, but "what fun is that?"
- My God, What Have I Done?: The jailer regrets being so mean to Mig when he realizes she’s his daughter.
- Nightmare Fetishist: Despereaux drew pictures of cats in his notebook, much to his teacher's (and parents') horror.
- Prophet Eyes: Hovis the thread-master, but only in the film.
- Serious Business: Soup. To the point the Narrator claims the people love Soup Day more than Christmas.
- Shout-Out:
- Boldo is a reference to Giuseppe Arcimboldo
, famous for painting detailed portraits of human heads comprised of other things (fruit and vegetables, flowers, animals). - The sewers are inspired on Hyeronymus Bosch's portrait of Hell, in "Garden of Delights".
- Princess Pea's design is inspired on Venus of Botticelli.
- The colouring and designs of the mice seems inpired on the pictures of Brueghel the Elder, who portrayed the common life of peasants.
- Boldo is a reference to Giuseppe Arcimboldo
- Spared by the Adaptation: Gregory the Jailer, as the rats chewed through his rope.
- Suicidal "Gotcha!": For the audience. The subversion of the Happily Ever After occurs while Despereaux is hanging from a window and apparently falls to his death. They later reveal him gliding away on his huge ears to his next adventure.
- Unreliable Voiceover.Narrator: First of all, rats hate the light. They spend their lives in the darkness. (A rat is shown looking right at the sun.)Narrator: They're also terrified of people, which is why they slink and cower all the time. (The rat walks right up to a human.)Narrator: And as far as telling the truth as concerned, well, that is impossible, because as everyone knows, a rat can't talk. (The rat begins speaking to the human.)
- Vocal Dissonance: The mice and rats speak with deep, human-like voices rather than the high squeaky one rodents have in Real Life. It is shown they do speak human language in-universe, so this is really is how they sound and not just for the listening pleasure of the viewers.
