Like any boy his age, Arthur is fascinated by the stories his grandma tells him before going to bed. His dreams are full of African tribes and incredible inventions of an old magic book that belonged to his eccentric grandfather, missing for several years.

When he starts to read it more thoroughly, Arthur realises that his grandpa left many clues about a treasure hidden at the back of their house. But Arthur discovers that the key to success lies in his own descent into the land of the Minimoys, creatures no larger than a tooth, whom his grandfather helped relocate to their garden. Somewhere among them is hidden a pile of rubies, too.

In order to safe his grandma’s house, Arthur decides to get into the Minimoys’ life and explore their seven kingdom world. However, in order to do so, there is only one solution- Arthur has to shrink and become a Minimoy himself!