Five years after the Viking village of Berk made peace with the dragons, they now live among the villagers as helpful companions. Hiccup goes on adventures with his dragon, Toothless, as they discover and map unexplored lands. Now 20 years old, he is being pressed by his father, Stoick the Vast, to succeed him as chieftain, although Hiccup remains unsure if he is ready for this responsibility.
While investigating a burnt forest, Hiccup and Astrid discover the remains of a fort encased in ice and encounter a group of dragon trappers led by Eret, who blames them for his fort’s destruction and attempts to capture their dragons for an insane conqueror named Drago Bludvist. The two dragon riders escape and return to Berk to warn Stoick about the dragon army that Drago is amassing. Stoick orders the villagers to fortify the island and prepare for battle. Hiccup, however, refuses to believe that war is inevitable. After Stoick interrupts Hiccup’s plan to get Eret to take him to Drago, Stoick explains that he once met Drago at a gathering of chiefs, where Drago, mocked after offering the chiefs his service in return for their servitude, murdered them all, with Stoick as the only survivor. Undeterred, Hiccup flies off with Toothless in search of Drago to try to reason with him.