Mumbo Jumbo lives safely and happily at home with his mother in the small valley. But one day everything is turned upside down when Mumbo gets injured by eating a magic mushroom and becomes enormous.

Fortunately, Frede, the mandrill monkey, has the solution to the problem, and suggests that they go on a long journey to find a cure. Mumbo Jumbo sets off on a dangerous journey with his three friends to find the scary witch Baba Yaga, so that she can make him small again. It is an adventurous journey that may make Mumbo Jumbo small again, but much bigger on the inside. Mumbo Jumbo must now learn to believe in himself and stand on his own two feet. Otherwise, it will be an unsolvable task.