14-year-old Nils Holgersson lives on a small farm in the very south of Sweden. Nils causes his parents a lot of grief because he is lazy and vicious: among other things, he constantly tortures and scares the animals on the farm. One day, at the end of March, Nils is transformed into a little gnome himself as punishment for a sneaky prank on a gnome. The farm animals don't miss this and, driven by revenge, they immediately want to attack the boy. At the same time, the tame goose goose Martin wants to join the wild geese who are coming over the Baltic Sea these days and want to fly to their breeding grounds in Lapland. Nils tries to stop the gander from taking off after Martin is the only one to protect the boy and the wild geese still mock Martin. But Nils doesn't succeed because he is too small and light and the gander simply takes off with the boy on his back. The wild geese are outraged by Martin's unasked-for trip: domestic geese are considered beneath their dignity by wild geese. Martin has to go to great lengths to prove to them that he is not a burden to the group and that he can complete the journey. After Nils has helped some animals in need over the next few days, the leader of the bird migration, the old one, arrives