Viggo has captured Heather and the Flightmare, and now Hiccup must outthink this dangerous new opponent.

The Riders learn from Heather that the Dragon Hunters are after the Flightmare. The Rides race to free the dragon. But could this be part of a larger scheme?

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

When a new tidal class dragon, the Sea Shocker, is found in Edge Cove, the riders must help it escape a group of hungry Scauldrons and reunite it with its migrating pod.

Tuff and Astrid continue to defend Dragon's Edge, while Hiccup, Snotlout and Johann discover an island full of wounded dragons that have been hunted and hurt by the Dragon Hunters.

When a distress call from Trader Johann arrives at Dragon's Edge, Hiccup, Snotlout, and Fishlegs go to investigate leaving Astrid, Ruff and Tuff to keep watch on the Edge. When Ruff is captured by Dragon Hunters, it's up to Astrid and Tuff to defend the Edge from a dragon hunter army.

Hiccup and the Riders must stop Ryker from creating a key to the Dragon Eye, which means a return trip to Glacier Island, this time to protect the Snow Wraith.

When Hiccup saves the Zippleback's life, the grateful dragon abandons Ruff and Tuff and follows Hiccup and Toothless around. Ruff and Tuff try to win their dragon back – with disastrous results.

When Snotlout and Astrid are given the task of transporting a ceremonial battle axe to a wedding between their two families, they must put aside their differences when the axe is taken by a new type of dragon – the Armorwing.

When Tuffnut is bitten by a strange creature, he believes he will turn into the legendary Lycanwing Dragon when the moon is full. Hiccup and the other riders must save him before Tuffnut goes off to live amongst the dragons forever.

Hiccup and Snotlout race to rescue the other riders from the Dragon Hunters.

When Stormfly is captured by Dragon Hunters, Hiccup and the riders have to find her and rescue her.

After Dagur attacks Berk, Astrid agrees to train a group of back up Dragon Riders. Little do they know they will soon be pressed into service.