During their search for the escaped Dagur the Deranged, Hiccup and the Dragon Riders discover a mysterious object - one that holds their destiny.
Hiccup and the Dragon Riders journey to Glacier Island to find the Snow Wraith, a fearsome dragon that holds the key to the Dragon Eye's mysteries.
The Dragon Riders discover a lush island that turns out to be the home of the Deathsong, a massive dragon that threatens to trap them forever.
On an island that will make the perfect outpost, the Dragon Riders discover that the indigenous residents are a mysterious new breed of dragon.
Thinking he's allergic to his dragon, Fishlegs gets hypnotized. He wakes up transformed into an invincible warrior known as Thor Bonecrusher.
When Dagur the Deranged captures Gustav, it's up to Hiccup and the Dragon Riders to get him back.
Fireworms invade Dragon's Edge, while Ruffnut and Tuffnut discover that they have an unexpected connection to the island.
As a Rumblehorn wreaks havoc on Dragon's Edge, Hiccup seeks the help of Stoick, who forms an unexpected bond with the rampaging beast.
Fishlegs and Meatlug liberate the Gronckles from a menacing dragon that has encroached on their ancestral home, Dark Deep.
The Dragon Riders are surprised to discover who is behind recent attacks on nearby ships - and to learn exactly what the ships are.
Heather joins the Dragon Riders, but it's not an easy alliance, especially when Hiccup uncovers a shocking secret about her true identity.
Hiccup and the Dragon Riders rescue a wounded Speed Stinger and take it back to Dragon's Edge, unaware of the dangers that follow.
When Hookfang is drawn to a female Monstrous Nightmare, Snotlout tries to break them up before he loses his friend forever.