During their search for the escaped Dagur the Deranged, Hiccup and the Dragon Riders discover a mysterious object—one that holds their destiny.

On an island that will make the perfect outpost, the dragon riders discover its indigenous residents are a mysterious new breed of dragon.

As a Rumblehorn dragon wreaks havoc on Dragon's Edge, Hiccup seeks the help of Stoick – who forms an unexpected bond with the rampaging beast.

When Hookfang is drawn to a female Monstrous Nightmare, Snotlout tries to break them up before he loses his best friend forever.

After an attack on Berk, Astrid trains a crew of backup Dragon Riders to battle back—but no one can guess how soon the next strike will hit.

As Hiccup and Snotlout race to rescue the others from the Dragon Hunters, they don't realize that someone close to them is working with the enemy.

Ryker is determined to create a key to the Dragon Eye, so he heads to Glacier Island to find the Snow Wraith that the Dragon Riders are protecting.

The Skrill returns with a vendetta against Hiccup and Toothless. Hiccup and the Riders must choose a new course of action to stop the vicious dragon.