The main character of the film is a little boy named Marek, who from an enemy of nature becomes its devoted friend. Before this happens, however, fate plays quite a trick on him. At first, however, nothing foreshadows this. Marek arrives in the forest with a school trip. He quickly separates himself from the rest of the children, after which he gives vent to his hooligan fantasy. He destroys an anthill, cuts a tree with a knife, tries to catch a spider. When he fails, he starts chasing a butterfly. He doesn't know that under this figure hides the prince of white and black magic. Wanting to punish the unruly boy, the sorcerer reduces him to the size of an insect. Mark, reduced to the size of an insect, must learn to live in completely new conditions. This is by no means easy.