Five years after the peace between people and dragon was mad in the Viking village, Hiccup and his dragon Toothless go on a new adventure. By accident, they discover an ice cave with a plenty of new wild dragons and the mysterious Dragon Rider as well. By the way, the two and the Viking village also unexpectedly fall in a battle with the dragon army led by an insane conqueror named Drago Bludvist. People and dragons of the village have to stand together to protect their peaceful lives.