Sarah gets in trouble at school when she fights a bully on the playground. As part of her punishment, she can't share the cook Rachel's freshly baked cookies with her mother and brother. The cookies are laced with a mysterious poison, and her brother and mother are rushed to the hospital. Sarah discovers that the poisoner was the evil Ratticus, king of the rats, and she sets off to Felinia to try to find the antidote. On her quest to save her family, she meets Princess Ratavia, daughter of the rat queen Sarah encountered in her first trip to Felinia. Unlike her evil mother, Ratavia is thoughtful, kind and considerate, everything that a rat is not supposed to be. With the help of Princess Ratavia, and Belle Starr, the Queen of the Cats, Sarah must escape the clutches of Ratticus, fight an army of cockroach minions, and find the herb that will cure her family. Along the way she learns that there is good and evil in every species, and that old enemies can become new friends.