Although Viggo keeps his promise about the Dragon Eye, Hiccup is unsure whether he can trust him as an ally against Ryker and the Shell Fire dragon.
To ensure the future survival of Mala's tribe, she and Hiccup must deposit a newly laid Eruptodon egg into the deadly Grand Volcano so it will hatch.
When a dragon that causes man-eating whirlpools threatens Berk's trade ships, the Dragon Riders must remove it without getting caught in its vortex.
When the twins fly to the Northern Markets to get Tuffnut's mace fixed, a chance turn of events lands them inside a secret Dragon Hunter operation.
