The Vikings don’t particularly keep track of the past. And that’s why when Hiccup Bloodthirsty Crowing Jerk III got tangled up in another story, he still didn’t know that he had, in fact, gotten tangled in the history of his tribe and his own family. And this story, by the way, has a direct connection to the near future—not just for Hiccup, but for the entire Barbarian Archipelago.
So, besides that, he had to do a few insignificant feats as usual: save friends (and a dozen outstanding Viking heroes at once), obtain a treasure, defeat a monster, and once again bring down an old enemy. A couple of trifles—if you’ve got a pesky and disobedient pet dragon!