Alvin reveals he trained the Screaming Death to attack Berk and destroy the island's inhabitants and only Snotlout and Hookfang can save Berk before it's too late. Meanwhile Hiccup gets ready for a final fight against Dagur to save Toothless and end the barbarians invasion of Berk once and for all.

Snotlout is expelled from the academy; Alvin returns to Berk to make amends.

Stoick is in need of learning how to ride a dragon, and he quickly insists on riding Toothless all the time. Meanwhile, a mysterious dragon has been attacking fishing ships.

Mildew has betrayed the Vikings of Berk and allowed Alvin the Treacherous to kidnap Hiccup and Toothless. Astrid and Stoick must rescue them from Outcast Island along with help from a new friend.

After getting his picture painted with his father, Hiccup begins to fear that he is not Stoick's ideal son, so to prove himself, he and his friends set out on a treasure hunt that even Stoick had not been able to complete.

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.

The kids go on a dragon survival-training mission to Dragon Island, where they encounter Dagur, the Berserker Chief, who has become obsessed with hunting the Night Fury.

Hiccup must help Astrid face her fear of the terrifying Flightmare, a ghostly dragon that seemingly "froze" her uncle with fear, shaming her family name. With Fishlegs' help, they discover that there's more to the Flightmare than meets the eye

The dragons unintentionally reduce Berk's food productivity by still scaring the living daylights out of the local livestock, and with the first winter storm coming, the dragon-riding Viking youths of Berk must try and familiarize the local animals with their Dragon companions.

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.

Certain that Alvin is planning an attack on Berk, Stoick institutes flight restrictions on the dragon academy. Hiccup, certain that Alvin will be using his newfound dragon-training knowledge to bolster his attack, forms a secret “Dragon Flight Club” in order to train the kids to defend Berk against Alvin’s dragon army.

Hiccup discovers that the town's water shortage has been caused by the Outcasts' plan to hide Whispering Death eggs under Berk, which soon hatch and tunnel under the island, threatening the villagers.

Hiccup and co. discover an injured Scauldron on the shores of Changewing Island. The kids must heal the dragon and return him safely to the ocean, before he falls victim to the elements, as well as the territorial Changewings.

When three adolescent Thunderdrums attack the village, only Stoick's Thornado can bring chaos to order.

A rogue dragon – a Whispering Death – shows up in Berk, tearing up the village. He's on a mission to find Toothless and settle a score. Despite Hiccup's efforts to help, Toothless insists on facing the dragon alone. But unlike their past battle, Toothless's inability to fly my prove to be his undoing.

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.

Hookfang is losing his ability to catch on fire, and it's up to Snotlout, Hiccup and the others to find the lair of the Fireworm Queen, which may hold the only possible cure, before it's too late.

When wild dragons start overwhelming Berk, Hiccup and Toothless discover islands are disappearing throughout the archipelago. When Hiccup and Toothless investigate the cause, they then encounter the Screaming Death.

Dragons are still dragons, and as a result, they are causing mayhem in the Isle of Berk. Stoick is reconsidering allowing the dragons to roam freely on Berk. It is up to Hiccup and his friends to convince Stoick otherwise.

Hiccup had discovered Mildew framed the dragons but has destroyed all evidence of it, therefore he must prove of their innocence in order to get them back. Meanwhile, Alvin the Treacherous of the Outcast Tribe are on the mission to raid the Isle of Berk in order to find and capture the "Dragon Conqueror".

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.

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

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

When the dragon riders discover a frozen Skrill, a lightning-powered dragon revered by the Berserkers, they scramble to get it off Berk.

Tuffnut goes undercover to help the riders rescue a Skrill.