The focus of the "Terra-X" -law for children is Opa Max (Jürgen Mai), a retired scientist who works on a time machine together with his grandson Paul (Elias Kassner). But instead of traveling by yourself, the not-quite-functional device brings people from the past into the present instead, who are pestered by Paul with questions. Themes of the first season include the ancient Egypt, Romans and Teutons, Cologne Cathedral and other medieval construction sites.