Hiccup and Toothless find an ice cave with new dragons and a Dragon Rider. They must protect their village from a battle with a madman and his dragon army.

In a village plagued by dragon attacks, a young Viking named Hiccup befriends a dragon and learns that their kind is misunderstood. Together, they defy societal expectations and help forge a new alliance between humans and dragons.

After discovering another Night Fury dragon, Hiccup and Toothless embark on a quest to find the Hidden World, a Dragon Utopia, before the tyrant Grimmel can reach it. Along the way, they face challenges, encounter new dragons, and strengthen their bond. As they navigate the treacherous journey, Hiccup and Toothless must confront their destinies and make sacrifices to ensure the survival of their kind.