Snotlout uses the Smothering Smokebreaths to get it back and the riders help the Armorwing when they pick apart its hide, earning its trust. Madeleine the midwife replaces his heart with a cuckoo-clock. Though Hiccup feels guilty for driving Viggo to make such a move, Stoick expresses confidence that he and the others will always be able to stop him. Meanwhile, Stoick and Gobber, left in charge while the riders are away, lose Tuffnut's pet chicken and each try to replace it with a new one. 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 find Ryker, he tells them that Viggo is setting them up and he can give them the Dragon Eye as the Berserkers are attacked by the Shell Fire, a giant sea dragon equipped with Hunter weaponry. Their group finally returns and meets the hunters' true leader, Ryker's younger brother Viggo Grimborn, who proposes a secret alliance with Heather in order to oust either Ryker or Dagur as possible traitors. The Screaming Death happened to be digging shafts underneath the islands that were large enough to cause the islands to collapse into the sea, forcing dragons to abandon their homes. Hiccup, after fiddling around with the eye, finds that it's activated by the fire of any Dragon and works as a light projector showing him maps, writing and Dragons he's never seen. They live on a volcanic island home to an enormous dragon called the Eruptodon. Ruffnut is captured by the hunters, whose armada is approaching Dragon's Edge, leaving defense of the island to Astrid and Tuffnut alone.
Hiccup still manages to free the Submaripper, and it rescues him just as the bell shatters, leaving Ryker to take a desperate Viggo away just as the other riders close in. They learn the tribe is guarded by a lava-eating dragon, the Eruptodon, whom Mala and the others label 'The Great Protector,' but Hiccup soon realizes when the Eruptodon is captured that Viggo was using them as a distraction. I anxiously await season 4 so that I can learn more about how things happened, before How to Train Your Dragon 2's timeline. The Viking teenagers must bring the twins back together to control their dragon and avoid provoking Dagur to war. 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.
Meanwhile the twins, Snotlout, and Astrid search for Chicken, who has gone missing, and find she has started a new family with a wild rooster. The riders find out the Hunters are forcing the Shell Fire to attack but are unable to get close as the attacks trigger the Edge's volcano. She trains the dragon and the gang are able to help it. They eventually learn the Rumblehorn has been attempting to warn everyone of an approaching tsunami and chase them off before the wave would wipe them all out. However, he states that they must compete against each other, as only one can prevail. The second and third seasons of Dragons: Race to the Edge premiered on January 8 and June 24, 2016, respectively.
Continuing his ruse as their ally, Johann suggests taking a trip to the Northern Market with Hiccup alone and that he bring both his Dragon Eye 2 and all of his lenses. 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 is captured by everyone from two dim-witted brothers to Savage to the masked man from Viggo's auction, leading the riders and Stoick on a wild goose chase to find him. Astrid is separated from Hiccup in a snowstorm and finds Heather camped out on a nearby cliff. It's so crisply drawn and fluid that a person of a certain age would be forgiven for wondering how on earth we survived with things like Scooby-Doo and The Perils of Penelope Pitstop. To make things worse, the ingredients needed to cure the illness are in Toothless' satchel and all but Fishlegs are caught sick.
Ryker is physically stronger and more stubborn than his younger brother. In the end, the twins, who have been pranking everyone without end, receive retribution by the rest of the riders. After much effort they finally get it open and Hiccup is able to retrieve the device from a distracted Dagur. In order to get the book back from Alvin, Astrid disguises herself as Heather and goes into Outcast Territory. Hiccup is captured by Ryker and Dagur but is rescued by Barf and Belch who in turn are rescued from drowning by the twins, repaying the debt and returning everything to normal. Hiccup is determined to finally best Snotlout, who constantly gloats about being the reigning Thawfest champion, but Hiccup's successes begin to make him arrogant and boastful, much to Astrid's displeasure and disappointment. Hiccup refuses, but Viggo reveals that he has poisoned Toothless with Red Oleander, and that Toothless will die in three days if they do not recover an antidote from Johann.
After hearing this, Astrid starts to think that Hiccup isn't interested in her anymore since they are not as publicly affectionate as Dagur and Mala and begins to question her relationship with him. Get ready for jaw-dropping twists and turns as finally unearths the of the , an makes a sacrifice for the Riders, and the fate of all dragon-kind is put at risk. The teens have to stop the Screaming Death before it reaches Berk. Using a Skrill as a diversion, Hiccup and Viggo enter their headquarters where Viggo betrays Hiccup to earn favor with Johann and Krogan once more. Stormfly and Toothless share a friendly rivalry in most of the competitions Hiccup and Astrid devise.
Astrid and Snotlout must grudgingly work together to find the cause of the feud, if they want their dragons to stay in the academy. The island where the gold is stored turns out to be empty save for strange looking ruins, and the others are captured by Viggo while searching. Later, an injured Heather and Windshear return from Vanaheim with dire news. Meanwhile, Fishlegs discovers Dragon Root, which could end up affecting not just Stormfly and Hookfang, but all their dragons. Upon investigation, they discover it to be a young adult Seashocker having drifted into the cove after being separated from its pod.