Sophie is also Bea Garcia’s best friend ever. They both love peanut butter cookies and hanging out in the crabapple tree in the backyard. They also like to snuggle together and dream of all sorts of adventures. Bea and Sophie also share a strong dislike for Bert, the monster next door. When Bea's teacher makes her visit Bert for a school assignment, Bea brings Sophie along for extra security and comfort. But even monsters have pets, and Bert has a terrible one: Big Kitty. When Big Kitty attacks, Sophie jumps out a window and sprints away—far from Bea! Bea goes on a frantic search for her best friend but Sophie is nowhere to be found. Will Bea's best friend ever come home again?