To prove they're on the same side and pose no threat, the Dragon Riders try to rescue Queen Mala's dragon, which Viggo stole to destroy Dragon's Edge.
Tuffnut is eager to impress his visiting cousin, Gruffnut. But Ruffnut is suspicious of his real reasons for coming to Dragon's Edge.
The Dragon Riders attend Berk's 400th anniversary celebration, where a bounty on Hiccup's head casts a dark shadow over the festivities.
After getting bad advice from his father, Snotlout tries to seize leadership of the Dragon Riders and starts making reckless decisions on his own.
Hiccup and Heather are shocked to see Dagur among the Dragon Hunters. Snotlout undergoes the Trials, a series of tests he must pass to be Mala's king.
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.
With his teammates grounded due to lack of sleep from the midnight sun, Hiccup tries to help a hurt dragon alone, but suddenly gets in over his head.
When Dagur appears at the Edge claiming to know where Viggo keeps his gold, the Dragon Riders fly off to find the stash and return Berk's stolen gold.
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 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.
While rescuing the dragons from a fire in the stables caused by a powerful lightning storm, Astrid suffers an injury that leaves her blind.
After months of planning, Hiccup launches an operation to capture the Dragon Eye from Viggo, only to find that someone else has beaten them to it.
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.