Season 1 - Episode Guide

Having made peace and now living among the Vikings, the dragons' natural behavior leads to chaos on the Isle of Berk. This causes Stoick to reconsider allowing the dragons to roam freely on Berk. It is up to Hiccup and his friends to convince him otherwise.

The peace with the dragons has put Gobber out of business as a weaponry blacksmith. Feeling responsible, Hiccup tries to help find a new job for Gobber, however Gobber's slightly eccentric and overenthusiastic personality makes this difficult.

The dragons unintentionally cripple Berk's food productivity by terrifying the local livestock, and with the year's first winter storm coming, the dragon-riding Viking youths of Berk must try and familiarize the local animals with their dragon companions if they are to have enough food for the winter.

Hiccup finds an injured baby dragon in the woods. Noting that this dragon is an undocumented species, he takes it in for care and closer study. The teens name it a "Typhoomerang", but Toothless appears jealous and does not warm up to the energetic newcomer. Meanwhile, the baby's mother makes her way toward Berk to find her lost son.

The dragons are blamed for vandalism, and Hiccup tries to prove their innocence by forming a night patrol called the "Dragon United Monitoring Brigade" (DUMB), but not in time to prevent the dragons' banishment from the island. Hiccup begins to suspect that Mildew is responsible for the damage.

Continuing from the previous episode, Hiccup attempts to find evidence that Mildew caused the damage to the village, hoping to exonerate the banished dragons. Meanwhile, Alvin the Treacherous of the Outcast Tribe launches a raid on the Isle of Berk in order to find and capture the "Dragon Conqueror".

Hiccup convinces Stoick to ride a dragon to aid him in his duties as chief, but he quickly insists on riding Toothless on a regular basis, to both Toothless and Hiccup's dismay. Meanwhile, a mysterious dragon has been attacking the tribe's fishing ships.

A traditional painted portrait of Berk's Chief and his son exaggerates Hiccup's muscularity and size and causes him to worry that he is not Stoick's ideal son. Hiccup is determined to prove himself by accomplishing the treasure-hunting quest of Hamish II, a quest that even Stoick and Gobber had not been able to complete.

Immediately after the visit of the renowned Trader Johann, all dragons on the Isle of Berk are mysteriously falling ill. When Mildew is discovered responsible, he is forced to help Hiccup, Stoick, and Gobber find and capture a ferocious water dragon called the Scauldron in order to concoct an antidote before it is too late (after the Scauldron bites Mildew's butt).

The teens of Berk find a mysterious girl named Heather on Thor's Beach. While Hiccup and the other teens openly welcome the newcomer, Astrid's jealousy turns to suspicion when she notices Heather is taking an unusual interest in the Book of Dragons. Unfortunately it is found she was working with the Outcasts and, despite the Dragon Riders' effort, she manages to give the ancient Book of Dragons to Alvin.

Heather's betrayal to Berk caused the Book of Dragons to fall into Alvin the Treacherous' hands, and Heather's imprisonment on Berk. In order to get the book back from Alvin, Astrid disguises herself as Heather and goes into Outcast Territory. Towards the end of her mission, Astrid learns and confirms Heather's true motives for helping the Outcasts-freeing her parents.

Berk's annual festive sporting competition, the Thawfest games, is underway and all the teens are participating with the dragons for the first time in Viking history. 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.

Sudden lightning storms are endangering the residents of Berk and it is believed that Thor is angry at the island. Mildew leads the superstitious villagers into blaming Toothless, "the unholy offspring of [lightning] and death itself", for the lightning, leaving Hiccup to find the true answers for Thor's sudden destructive anger.

Toothless encounters a Whispering Death, that happens to be a rival from his past. Blinded by their grudge against each other, Toothless runs away to confront the rival alone. Hiccup must find Toothless and reason with him before the rivalry turns fatal.

Dagur the Deranged visits Berk to renew a peace treaty between the Hooligan Tribe of Berk and the Berserkers, and the dragons are put into hiding to dispel rumours that Berk is training a dragon army, which will make Dagur cancel the treaty. But when Ruffnut and Tuffnut begin to fight, their dragon, Barf and Belch, is left out of control. The Viking teenagers must bring the twins back together to control their dragon and avoid provoking Dagur to war.

Caught in a waterspout, Toothless' prosthetic tail is damaged, rendering him unable to fly and thus leaving him, Hiccup and Snotlout stranded on Outcast Island. The three must work together to repair the damage, overcome the rivalry between Hiccup and Snotlout and return home to Berk before they are captured by Alvin and the Outcasts.

When Hiccup discovers Trader Johann's ship was shipwrecked in a rumored haunted bog with a gift made for him by his mother, he will stop at nothing to retrieve it -not even being followed by a "fog monster".

When Snotlout and the villagers mistake color-changing dragon eggs for gems that bring good fortune, Fishlegs, who is responsible for the eggs' discovery, must take a stand against Snotlout,who is trying to sell the eggs, and reunite them with their Changewing mothers before they destroy Berk.

During Berk's annual Bork week celebrations, Hiccup is granted access to Bork the Bold's private and personal archives. 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. After discovering that the Bork notes are fakes made by the Outcasts, the duo tries to flee, but are captured by Alvin.

After being captured, Hiccup discovers that Mildew has joined the Outcasts. However, Mildew is also imprisoned when he's no longer of any use to Alvin now that he has Hiccup. Hiccup reluctantly allows Mildew to help him find Toothless and escape Outcast Island, a final test for Mildew's loyalty to Berk. After Hiccup and Toothless escape, Mildew betrays the Dragon Riders, revealing that Mildew's imprisonment has also been a trick, allowing Alvin to train a Whispering Death.