There is a book that teaches how to be a bully and it's about to ruin Eric Haskins life. Upon entering 5th grade he is mercilessly tormented by a group of boys that turn the entire class against him. But Eric hears a conspiracy theory about "The Bully Book," a manual that has been passed down from 5th grader to 5th grader throughout the years teaching how to be the coolest kid in school. The lynchpin of the system is the selection of the Grunt, one kid to be lowest of the low. Eric becomes a detective of the book, following a paper trail, seeking out older Grunts, hoping he can discover why he has been chosen. If he can discover why he's the Grunt, maybe he can change himself and escape from his terrible fate.
The Bully Book is told in alternating journal entries by Eric, and actual pages of the mysterious Bully Book itself.