Three years after the war with the Berserkers, Hiccup and his friends are enjoying the peaceful life. But when Dagur the Deranged escapes from prison and plan to build an armada in the uncharted territories to seek for revenge on Hiccup, Hiccup and his dragon riders have to search the region to look for both Dagur and hitherto unknown species of dragons, leaving Berk alone building a new and distant base of operations called Dragon's Edge for them.