Phoebe, a fourth-grader who likes to play video games, wants people to think that she is special. But all she seems to do is attract criticism from kids like her archenemy, Dakota, who calls her names like "stupidhead." That changes when Phoebe accidentally meets a unicorn named Marigold Heavenly Nostrils. Marigold uses her "shield of boringness" to remain invisible to most people, but not to Phoebe and some of her companions. Having a friend like Marigold accomplishes Phoebe's desire to be special, but, as Phoebe soon finds out, there are strings attached. Marigold hasego problems of her own, such as becoming mesmerized by her own reflection in a pond and reveling in the fact of her own "awesomeness." Nevertheless, life changes for the better for Phoebe as she introduces Marigold to the pleasures of slumber parties, dinner with her parents, the start of school, piano lessons, and a number of other adventures.