Friends Franzi, Marieave and Kim planned to spend the summer rehearsing for a Peter Pan play, but when strange things start to happen at the theatre they take on the role of investigators.
Police officer Hella Christensen is on her way to her new job in Kiel. But she doesn't get far because a dead girl was found at the pier in her hometown. Hella's new superior, Simon Kessler, has already arrived from Kiel and is awaiting her on the bridge. Hella recognizes the dead person immediately: it is 14-year-old Jenni, daughter of her neighboring family. Kessler orders the recently defunct local office to be used to investigate the murder.
13-year-old Nils Holgersson is bored living on his parents' farm. Instead of helping with the work, he prefers to play pranks and tease animals, and he really wants to spend more time with Asa, a beautiful girl. One day his life actually changes: he meets an elf who shrinks him to its size. What's more, Nils begins to understand animals and communicate with them. Gasior Bataki Martin and Raven became his friends. When Martin flies to Lapland with a group of geese led by the wise Acre, Nils willingly joins them. Aka is confident that this will help Nils become a better person and thus regain his regular height. Meanwhile, Asa travels to Lapland to find Nils.
A chance encounter throws a young engineer into the depths of a deadly conspiracy that leads to the crash of the Hindenburg zeppelin in 1937.