Holger discovers mysterious notes in an old geography book that lead him to Oslo and an enigmatic key.

Holger is finally reunited with his old friend Mortensen.

Holger and Mortensen continue their journey and meet a mysterious man in a lighthouse.

Newly found clues lead Holger and Mortensen to southern Norway. Mortensen is doubtful if he still wants to be involved. Holger realizes that they are not alone in searching for the map's secret.

Holger and Mortensen have arrived at Borgund's stave church. There they find another part of the map with another riddle that takes them further north.

Holger and Mortensen are on Svalbard, almost as far north as you can get. In an abandoned mining town, the pursuers catch up with them, and they are forced to flee.

While Mortensen is recovering from his injury, the old woman Sirpa decides to train Holger to become a master geographer. With Sirpa's echo and newfound strength, they make their way south through Finland's vast lake system.

After the Brotherhood of the Black Sun steals the map, Holger and Mortensen learn that Mary Diana is on an island. Instead of aiming to take the map, they try to find and save Mary Diana.

Holger travels to Iceland to try to reach the place where Gjallarhornet is supposed to be before von Troppeln. Holger reaches the large and terrifying lava area of Dimmuborgir. Here the final battle will take place.