When baby Billy Monster is born, his father proudly declares that his son will grow up to be the worst monster in the entire world. Big sister Hazel is not happy about this at all. She has always been incredibly talented at growling, bending iron bars with her teeth, and scaring the mail carrier. Yet, since the new baby arrived, nobody seems to notice Hazel's impressive monstrous skills anymore. When baby Billy actually wins the Worst Monster in the World contest, Hazel decides she has had enough. She sets out on a determined mission to prove to her parents that she is truly the most terrifying and worst monster in the family. This funny sibling story highlights the classic struggle for attention.