In "Ratburger" by David Walliams, the story revolves around a young girl named Zoe who is facing numerous challenges in her life. One of the main characters is the villain, Mr. Mean, a cruel and unscrupulous fast-food entrepreneur who exploits animals and children alike. He is greedy, selfish, and represents the negative aspects of commercialization.

Zoe adopts a pet rat named Armitage, who is both cute and clever. Throughout the story, Armitage becomes a key figure, as Zoe tries to save him from Mr. Mean’s plans. The narrative blends humor and adventure, emphasizing themes of friendship, resilience, and standing up against bullies.

Walliams’ signature style is evident in the colorful and exaggerated descriptions of characters, which add to the book's charm and appeal to young readers.