Secret Files: Tunguska Team: Nina is torn from her day-to-day routine when she finds out her father has disappeared without a trace. As the police cannot help her (or will not?), Nina sets off to look for clues as to her father's whereabouts. She thereby meets Max Gruber, a young colleague of her father who spontaneously offers to help the attractive young lady. Both quickly find out that Nina's father had something to do with an expedition to Siberia which was carried out to research into the causes of the mysterious Tunguska catastrophe of 1908. At that time a mighty explosion triggered an inferno and the causes remain a mystery until today.

Nina and Max soon realise that the events back then must have something to do with her father's disappearance. The search for answers leads Nina and Max to the most remote corners of the world (Berlin, Moscow, Cuba, China, the Antarctic etc.). It soon thereby becomes clear that powerful adversaries are also interested in Nina's father's secret. In the end it becomes clear that there is much more at stake than just the disappearance of an old man.