Holger Nilsson is forced on a raging treasure hunt to find the seven keys to his world-famous relative Mary Diana Graaf's mythical laboratory. To help him, he has the inventor Mortensen and Mary Diana's quirky GPS computer with pre-recorded riddles and clues written in verse. But what kind of mysterious and malevolent figure lurks in the background?

Join Holger and Mortensen in search of an ancient treasure - the Gjallarhorn! The journey goes through the Nordic region, from Danish Funen in the south to Svalbard in the north. The secret brotherhood The Black Sun also hunts for the fabled treasure.

A young woman lost her memory after an accident. In the woman's bag is a note with Holger's address.

Join us on a breathtaking adventure through the world's different climate zones and its natural types. We meet old and new heroes - Mortensen, Esmé, the young Flora and her grandfather Georg Graaf - who left behind a strange secret. The mystery leads to an ancient map that seems to be related to an ancient myth about the mighty kingdom of Atlantis.