In this adventure, a gigantic Dragon swims to the shore of Berk, called the Dreader. The Vikings have heard many tales of the dreaded Dreader, and stay on Berk until it leaves. In the meantime, they finish off all the food on Berk, leaving them with only limpets. So, they starve. After 6 weeks, the Dreader still does not leave, prompting Stoick to hatch up a clever and intelligent plan, which involves them attacking the Dreader. Hiccup's plan to ask the Dragon what it wants is denied by Stoick, and they attack the next morning. Meanwhile, a hungry Toothless realizes that he left 3 eggs buried near the Great Hall and decides to boil them while the Vikings are gone. To his dismay, the eggs hatch, popping three teeny-weeny little Dragons who mistake Toothless for their Papa.
As Toothless sees Fireworm flying nearby, he decides to let her eat the Dragons as they are pestering him. Hiccup, who is on the Fat Penguin with Fishlegs, is trying to ask the Dreader what it wants, and the plan goes wrong. The Dreader screams, and says that they have stolen its future. It then sprays very nasty liquid on the Vikings, leading Hiccup to believe that all the stories about the Dreader are exaggerated and that it is just a giant Stinkdragon. Toothless decides to save the small Vragons and they wreak havoc on Hiccup's house. As they sail back to Berk, now unafraid of the Dreader, Hiccup notices a column of smoke from his house and rushes in only to find the three Dragons. After one of them spits some foul smelling liquid at him, Hiccup deduces that the Toothless accidentally stole Dreader eggs and the Dreader is angry. Hiccup gives the Dreader its children and all is well again. Stoick orders Fishlegs to write a saga about the Day of the Dreader, exaggerating its powers and with a Mighty Stoick battling it.