Fribble Mouse and his brother Scamper live in Cheddarville, Wisconsin. Both are extremely curious. When faced with a mystery, they seek out information at the public and school libraries. Their nearest neighbor is Mr. Crumb. When he takes up a new hobby, he says it will be his secret until he can be expert at it--unless Fribble can figure it out ahead of time. Using their library skills, Fribble and Scamper accept the challenge.