While ten-year-old Arthur tries to save his grandfather's house from demolition, he goes in search of a stolen treasure and discovers the land of the Minimoys, a tribe of tiny people.
After receiving a call for help, Arthur enters the underground world of the Invisibles to defeat the evil wizard Maltazard and save Princess Selenia and the Minimoys.
A young boy, who must find his grandfather in order to pay off the debt on their house, turns to the help of tiny but magical creatures called Minimoys and sets out on the adventure of a lifetime.