The Outcast leader, Alvin, is kidnapped and held for ransom by bandits. They call on the Dragon Riders to request the assistance of Thor Bonecrusher.

After the Edge is ambushed by a group of Singetails, the Riders quickly take flight to ward them off, but are shocked when they get a closer look.

The Riders flee to Berk, where Stoick's plan for defeating the Flyers, which will require a painful sacrifice, spurs Hiccup to seek an alternative.

While visiting Wingmaiden Island, a baby Razorwhip bonds with Ruffnut, who suddenly finds herself trying her hand at being a Wingmaiden.

When the Flyers try to kill him because he's no longer useful, Viggo forces Hiccup to help him get revenge by stealing their Dragon Eye and lenses.

After learning Krogan is using a Deathsong to lure and subdue Singetails for his growing army of Flyers, the Riders set out to rescue the dragon.

The Riders race to the home of the true King of Dragons. But the Flyers are already there, and they soon come face to face with the legendary creature.