It featured a family of tiny but intelligent humanoid creatures with mouse-like features (the Littles) who live in a house owned by the Bigg family. The mouse-like features include a long, furry tail, long teeth and mouse-like ears. Their height is 4-6 inches. The Little family consists of Frank and Helen Little, their children Tom and Lucy, and Grandpa Little.
Henry Bigg is the boy who lives in a house with The Littles. He is one of the few humans who knows of the Littles' existence. Dr. Hunter is an evil scientist who makes several attempts to capture the Littles so that he can expose them to the rest of the world and thus become rich and powerful. He is also depicted as being Henry's arch-nemesis. Peterson is Hunter's main (and only) henchman and sidekick. He assists Hunter in his every dark attempt to capture the Littles.