Heather meanwhile tracks down Dagur alone but is captured by his new armada. However, Hiccup had already deduced Johann was the mole thanks to the twins and is able to escape thanks to Toothless. The Shell Fire is freed and Ryker is consumed with the fleet by the Submaripper, while Viggo turns on Hiccup threatening to kill Astrid in exchange for the Dragon Eye, but Hiccup throws the Eye into the volcano and Viggo rushes to his doom chasing after it. In an attempt to free their dragons all of the group apart from Hiccup get trapped by the dragon. After the group traps the leader dragon they realise how much danger the rest of the dragons are in when Changewings begin attacking them. Tuffnut learns to put the needs of the team before his own and saves the others by sacrificing his Macey and freeing the others.
According to , executive producer for How to Train Your Dragon, the series was planned to be much darker and deeper than 's previous television series spin-offs, with a similar tone to the movie. The riders and Berserker siblings battle, and despite Savage capturing Heather, still manage to defeat him, and Dagur, admitting Gustav's apprenticeship was faked to relieve Berk of him for a while, honors Snotlout with a Berserker trophy, though he purposefully gets his name wrong. Hiccup allows himself to stand trial and face their punishments, seeing Mala and her tribe as potential allies in their struggles against the hunters and eventually wins her trust. When he finds information and a map about an island inhabited by Night Furies within Bork's notes, Hiccup is determined to bring Toothless to his family. Upon investigation, they discover it to be a young adult Seashocker having drifted into the cove after being separated from its pod.
It's dangerous behavior forces the other Gronckles to leave and seek refuge on Dragons' Edge, much to everyone's dismay. Just as they are about to imprison the Skrill again, Hiccup decides against it, and the Skrill is set free. They deliver the axe late only to discover a fight broke out and the wedding was cancelled. In the end it was revealed that Stoick missed Thornado but in turn comes to bond with the Rumblehorn, who becomes his new dragon Skullcrusher. De Marco January 8, 2016 2016-01-08 Spitelout comes to Dragon's Edge to announce a union between the Jorgenson and Hofferson clans and charges last pick Snotlout with delivering the Jorgenson family axe to the Isle of Frigga for the ceremony. Hiccup uses his flight suit to win the trust of the wild dragons and leads them in a counterattack that fends off Ryker and his group.
They suddenly realise that the Night Terrors, under the command of their Alpha, a white Night Terror, need to flock into a shape of a giant version of themselves or any other dragon they wish as a defense mechanism to scare off threats or predators. Though Ryker attempts to break them by showing their dragons imprisoned, the riders hold their silence. While down there, Johann and Krogan decide that Viggo is no longer useful and collapse the cave entrance leaving him trapped with a Monstrous Nightmare. A trade takes place, but Gustav decides to stay with Dagur. Hiccup must find Toothless and reason with him before the rivalry turns fatal. Help comes from an unlikely source when Dagur appears and guides Hiccup and Toothless to his hideout, where he explains that he has been living in exile since leaving the hunters and claims to be reformed.
While searching the island for more, they discover a group of hunters, who are following the teachings of his ancestor, Ingard Ingerman in trapping Dramillions and using them to help train new recruits. Hiccup, Fishlegs, and the twins comes across a marble mining operation on a nearby island using trained Catastrophic Quakens, and while Fishlegs is determined to save them, Hiccup fears it may already be too late. With Spitelout's help, Hiccup discovers weaknesses in the Singetails' behaviours while the Riders, Stoick, the A-Team, and the Berk fleets launch a preemptive strike on Dragons' Edge where the Hunters are. Determined to win back Dark Deep for the Gronckles, Fishlegs allows Snotlout to train him in fighting dirty behind Hiccup's back in order to beat the Quaken and drive it off, but quickly find themselves outmatched once they confront it directly. Hiccup and Toothless decide to face against it one on one and later lead it into a trap, but the Skrill anticipates their plan and traps them instead.
They discover that the village has been overrun by Speed Stingers, a non-flying dragon that move at blindingly fast speeds and can paralyze their victims with their tails. This, however, turns out to be a trap by Krogan and the Hunters, who capture Windshear and demand the gem on Heather's belt, a lens for the Dragon Eye, in exchange for her life. They realize that they are being sent on a wild goose chase and their absence leaves Berk vulnerable to an attack by Krogan, who proceeds to take over Berk with his Flyers. Mala is finally convinced that the riders are allies of the dragons and the two groups align to defeat the hunters for good. The Berk forces are quickly put on the defensive and Krogan takes the chance to launch all his Dragon Flyers against them, which ultimately leaves them defenseless when Hiccup returns to turn the tide. They discover Garff safe and unharmed, but decide that they must liberate the Deathsong and cut off Krogan's supply of Singetails.
In their absence, the Edge is attacked by a group of Singetails, which the others discover are being ridden by the Hunters and led by Krogan and his Titan Wing Singetail. The riders are cornered in trying to release it, but receive unexpected help from the Skrill itself in sending the hunters away. When the riders go on a mission to destroy the hunters' increased supply of Dragon Root, Snotlout at first refuses to go, but returns to save the riders when he discovers the trap that has been set. When the hunt begins, Fishlegs and Astrid combine Meatlug and Stormfly's fire to destroy the shackle that grounds the Dramillion. When the Queen and riders all unite, it proves to be too much for the invading Crasher, and it retreats.
Astrid and Ruffnut reconcile and the riders lead the wild dragons to a new home on the Edge. Hiccup plans to use the Flightmare's mist to paralyze the hunters, but Viggo's advanced tactics allow him to escape with the Flightmare, Heather and Windshear as captives, leaving Hiccup to wonder about their dangerous new opponent. Even Hiccup and Astrid's return does nothing to even the odds and things become worse when Fishlegs is separated from the group, though manages to return with help from his old friend Darkvarg. The Scauldron rebuffs their attempts for help, so no one but Ruffnut seems to calm it down. Using a supply of bolas from the ship, they lure the Flyers into a storm, causing the Flyers to be struck by lightning. It is revealed that Heather is acting as a spy and she gave Astrid the information, but when Astrid proposes that they tell Hiccup the truth, Heather declines. Despite their competition through the three challenges, Ruffnut decides to save Tuffnut instead of completing the final challenge, which Gruffnut reveals was the secret, fourth challenge: putting family above everything else.
The teens must drive the Screaming Death and the Whispering Death hatchlings away from the village before they destroy Berk. Astrid gains her sight back thanks to Gothi and she and Hiccup enjoy a perfect moment together, finally beginning their relationship. Hiccup develops a diving bell to dive underwater and Changewing Acid to dissolve the chains, but the Hunters' interruption wakes the sleeping Submaripper. After finding her, the riders scour the beach and the wreck of the Reaper for clues on their whereabouts, but only find a new lens for the Dragon Eye that works with a Changewing's acid. Only Hiccup and Snotlout manage to escape while the others are captured. In the commander's quarters of 'The Reaper', Hiccup finds a very mysterious device and after a struggle with Dagur all of the group, apart from Hiccup, are trapped in a cage. Snotlout manages to undo the hypnosis, but Fishlegs pretends to be Thor long enough for the other Riders to swoop in and rescue them and Alvin.
Though still doubtful, Hiccup and the others scramble to keep the siblings from noticing each other by sending Heather away while offering Dagur a Gronckle he names Shattermaster to get him to leave, but they cross paths anyway. Hiccup and Stoick admit their fault in taking on their burdens alone and promise to confide in each other as allies as well as family. Once out of the cave, the Riders destroy the Flyers' facilities and free the Singetails. Though Astrid is poisoned herself to gather the venom needed for the antidote, it proves ineffective on Stormfly, which turns out to be due to her never being poisoned and instead is grieving over the loss of Garff. They learn that Dagur has been working undercover trying to save Shattermaster from the Hunters, convincing the two to help him save his dragon and the captured Gronkles. In the end, the twins, who have been pranking everyone without end, receive retribution by the rest of the riders. Jones Jack Thomas June 24, 2016 2016-06-24 Hiccup and the riders are preparing an attack on a hunter shipyard when Dagur appears, asking for Hiccup's help to find Heather.