Unlike other skibbereen (or tooth fairies, as we know them), What-the-Dickens was born without siblings, and without knowing his purpose. His only motivation is finding a gift for the cat that tried to eat him (and see how confusing that could be), he embarks on a tale that brings him into contact with birds, tigers, humans, and other skibbereen. That's how he meets Pepper, in the middle of her job, exchanging a tooth for a coin. He is dragged back to headquarters with her, but soon discovers the world he knew nothing about isn't as welcoming as it first appeared. Many mishaps and adventures come from his own lack of knowledge.
What-the-Dickens' tale is told to distract Dinah, Zeke, and Rebecca Ruth from the terrible truth of the storm outside--a storm that has wiped out all contact with the outside world--and the fact their parents are missing. The book switches between present time, and What-the-Dickens' story.