Hiccup (voiced by Jay Baruchel), a young and brave Viking warrior, tamed a wounded dragon and became friends with it. After five years, the life of the residents of Berk Island has been completely permeated with the breath of dragons. Berk Island is now a paradise where Vikings and dragons coexist peacefully. However, growth means responsibility. In order to find the answer, Hiccup and the loyal Toothless began their adventure, but the result was beyond expectations. On the one hand, Hiccup discovered that the mysterious dragon trainer was none other than his long-lost mother Valka (voiced by Cate Blanchett); on the other hand, the power-hungry Dregg (voiced by Djimon Hounsou) and the dragon hunter Eret (voiced by Kit Harington) formed an alliance, threatening the peace between people and dragons on Berk Island. In order to protect the beloved dragons, Astrid (voiced by America Ferrera), Gobber (voiced by Craig Ferguson), Viking friends: Slug (voiced by Jonah Hill), Fishlegs (voiced by Christopher Mintz-Plasse), and the twins Ruffnut (voiced by Kristen Wiig) and Tuffnut (voiced by Todd Joseph Miller TJ Miller) all lend a hand, along with Hiccup, his father Stogle (voiced by Gerard Butler), the leader of the tribe, and his mother. During this time, the answer Hiccup has been looking for appears in an unexpected way without him realizing it...