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.

Upon losing a stupid bet Astrid has to kiss Hiccup every day for a whole miserable week, but Alvin and some other villains soon mess things up, big time. It gets even more complicated when it turns out that they're after Astrid who happens to be the key to all the ancient dragon secrets - she just doesn't know about it yet.

Being the son of the chief takes brains, courage, and a lot of patience. But at his father's the request for marriage, Hiccup decides he has had enough. When he seeks out a life of ease, he runs into more than what he bargained for.