Hiccup was banished from Berk for five years after Toothless. He spent banishment traveling the world with Camicazi and her Lightfury Rosie until they are forced to go to Berk by a looming enemy. The teens and Stoick are eager to know about Hiccup's past but he is unwilling to tell. What happens when a chief from the tribe called Hammer Fists arrives? What is Hiccup hiding and why?

The Red Death is defeated, and Berk is at peace. However, a new evil lurks in the archipelago, one that threatens all life on earth. Hiccup and Toothless mysteriously vanish, and Berk is caught up in a terrible war that lasts for years. All seems lost, but a man returns on the back of a Night Fury, with a black mask and a flaming sword. Rated T for violence and mild adult themes.