The riders race to the home of the true King of Dragons. But the flyers are already there, and they soon come face to face with the legendary creature.
The Riders and the Flyers go to Dramilion island, led by the complete dragon eyes. And again, Hiccup realizes that Johann and Krogan are one step ahead of him and struggles to catch up.
Heather's brother Dagur shows up out of no where and asks Hiccup for help finding her. He wants to learn to ride dragons. Dagur sees Heather on the edge and goes the extra mile to protect her.
When Astrid and Stormfly making an unusual discovery on a fishing boat, Astrid's life becomes dependent on one dragon, supposedly extinct. Can Hiccup find one of these peculiar dragons and save Astrid in time?