Youthful Hiccup and his cherished winged serpent, Toothless, face a dim risk when they become the pioneers of their networks. While hunting down new islands and winged serpents, Hiccup, Astrid, Toothless and Stormfly find Light Fury and a mythical beast underground world. Light Fury, a baffling mythical beast female, with uncommon physical qualities, expects to oppose the wild side of Toothless, which was numb in training. In any case, back in Arcapellago, Grimmel, a man who chases every Night Fury and Light Fury expects Hiccup to show Toothless and Light Fury. Can’t, he catches Light Fury and pledges to annihilate Hiccup and all his dear ones. At the point when the darkest risk they have ever experienced brings down their town, Hiccup and Toothless need to go out they know and travel in a concealed corner of the world, which is accepted to be only a legend . Hiccup, Toothless and his companions must go up against this new danger and search for another home where both they and the mythical serpents can live in harmony. As their actual predeterminations are found, the winged serpent and rider will battle together to the finish of the Earth to spare and ensure all their friends and family.