When Stormfly is captured by Dragon Hunters, a new villain emerges, Ryker Grimborn. Hiccup and the riders must find Stormfly and rescue her, before it's too late.
Hiccup and Snotlout race to rescue the other riders from Ryker and the Dragon Hunters. Little do they know that Dagur and Heather are now working with the Hunters.
When a strange creature bites Tuffnut, 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.
When Snotlout and Astrid are given the task of transporting a ceremonial battle-ax to a wedding between their two families, they must put aside their differences when a new type of dragon, the Armorwing, takes the ax.
When Hiccup and Toothless save the Zippleback's life, the grateful dragon abandons Ruff and Tuff, and follows Hiccup and Toothless trying to please them in any way possible.
Hiccup and the riders must stop Ryker from creating a key to the Dragon Eye, which means a return trip to Glacier Island. Only this time the Riders will be protecting the deadly Snow Wraith.
When a distress call arrives at Dragon's Edge; Hiccup, Snotlout, and Fishlegs go to investigate. Astrid, Ruff and Tuff stay behind to keep watch and defend Dragon's Edge from the Dragon Hunters.
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 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.
When Hiccup and Astrid learn that Heather has been taken into the confidence of the mysterious Viggo Grimborn, the Riders now have a real shot of bringing down the Dragon Hunters.