[1] The story takes place in East Cleveland, Ohio and tells the tale of an ingenious adolescent who develops a less expensive brand of toothpaste and how he and his middle-school aged friends work together to form a successful company.

The entire book is narrated by Kate MacKinstrey, who has recently moved to the city from Connecticut, and makes friends with Rufus at the beginning of the school year.

The duo sets up a small production operation in Rufus's basement and begins selling their toothpaste to friends, family, and eventually the entire town.

Their endeavor expands as Rufus issues stock, finds a proper factory and hires an adult employee, named Hector, to help manage operations.

Once Rufus has made his million, he retires from toothpaste manufacture, announcing he will spend the summer before his eighth grade year riding his bike to North Carolina to visit his grandmother.