One day, gnome Plop receives a letter from his uncle Knap. It states that Uncle Knap is very ill and that he can only heal if he drinks the juice of the Carbuncle root, but that root unfortunately only grows in Plop's forest and there isn't enough time left. Klus decides to build a real airship with which the gnomes can fly to Uncle Knap, but the journey is difficult and not without dangers..

Gnome Plop is having a spring cleaning in his mushroom together with his friends Lui, Klus and Kwebbel. While cleaning the chimney, Klus discovers an old treasure map which takes them on a big adventure, far from everything they have ever known..