Svante is a young boy who lives with his family in a Stockholm apartment. One day he meets Karlsson, a chubby little man in the prime of his life, who can fly using a propeller on his back and who lives in his little house on the roof.

After brothers Jonathan and Crusty pass away, they reunite in Nangijala, the land of eternal spring. Casting a long shadow over their world is the tyrant Tengil, ruler of the country Karmanjaka, where he’s building his new fortress up in the Ancient Mountains.