With Stoick a prisoner of the Berserkers, Hiccup is forced to ask Alvin for help. At the same time, the Screaming Death draws near...
Snotlout disobeys orders and is expelled from the academy. Alvin arrives in Berk to makeup, but no one trusts him.
When three adolescent Thunderdrums attack the village, only Stoick's Thornado can bring chaos to order.
The citizens of Berk must face a rogue species of dragon that steals all the metal it can find.
Toothless contracts the flu that is spreading throughout Berk.
With Hokfang and Stormfly fighting, the collection for the harvest is in danger.
When an ice storm hits Berk, Speed Stingers attack the citizens forcing them into hiding.
When the gang find an injured scauldron on Changewing island, they attempt to rescue it before further harm comes to it.
Gustav Larson fills in on Hookfang when his friend Snotlout doubts his future.
Tuffnut goes undercover to help the team rescue the Skrill from the Berserkers' grasp.
The riders find a frozen Skrill, a lightning powered dragon, and need to get it off Berk before the Dagur and the Berserkers find out about it.
While searching for dragon traps, Tuffnut falls into a trap with a forest fire bearing toward him. Fortunately, an old friend shows up to help.
Hiccup and friends discover that several islands have vanished, and that their old foe, the Screaming Death, is responsible.
Astrid sets out to confront the Flightmare, a dragon that shamed her family ten years ago.
When Hookfang's flame goes out, the riders must travel to Fireworm Island to reignite it.
When the village well runs dry, Hiccup and Toothless investigate. They soon discover a group of baby Whispering Deaths beneath Berk.
The team decides to practice, without their dragons, against wild ones and come across Dagur hunting dragons on the island.
After being left behind, Fishlegs and Meatlug overeat and discover that different combinations of stones cause Meatlug to produce different types of materials including glass, steel and magnets.
Certain that Alvin is planning an attack on Berk, Stoick institutes a ban on all dragon flying. 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.
The gang search for Hiccup and Toothless, discovering that both are severe peril from the outcasts.
All the dragon species have multiple individuals except for Night Furies, Hiccup finds a secret page in the book of dragons revealing to him a secret island where other Night Furies live. Hiccup and Toothless embark on a challenging adventure to the island, but what may lie in his path, only one can guess.
After Fishlegs find a rare gem, a group of Changewings follow him.
A mysterious fog has attacked Trader Johann's ship on his way to Berk and the group need to find it to get back a special cargo.
Hiccup and Snotlout differ in opinion during a mission and the two end up on Outcast island.
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.
Toothless encounters a rival from his past. Blinded by their grudge against each other, Toothless runs away in hopes to battle the rival alone. Hiccup must find Toothless and reason with him before this rivalry turns fatal.
Because the vikings' homes can't support the weight of the dragons, they install metal perches above the homes. However when lightning keeps striking the village, Toothless gets blamed for angering the god Thor.
The annual Thawfest games are starting and this year dragon events are included, which means Hiccup finally has a chance to win.
After the stolen Book of Dragons falls into the Outcast's hands, the teens learn that Heather's parents are in trouble and the trainers help her save them.
A mysterious girl washes up on the shores of Berk saying pirates attacked her family and then her island. While everyone else (especially Hiccup) accepts her, Astrid isn't as sure of her intentions. Could it be she is working for Alvin and the Outcasts willingly or under duress? Where is the Book of Dragons, tune in next week for the exciting conclusion to this story.
The dragons become sick and the gang try to cure them.
Worried Stoick is disappointed in him, Hiccup heads out on a treasure hunt to prove his worth.
Hiccup convinces Stoick that riding a dragon would make his life easier and teaches him how using Toothless. However when Stoick overworks Toothless, they need to find him a dragon of his own.
With the dragons gone, Alvin and the outcasts are poised to attack.
The dragons are falsely accused of vandalism and banished from Berk, leaving the island vulnerable to an attack by Alvin and the Outcasts.
Hiccup finds an injured baby dragon,but Toothless does not warm up to the energetic newcomer. The baby's angry mother, meanwhile, makes her way toward Berk to find her lost son.
While racing during "dragon boarding", Hiccup and Astrid cause an avalanche and end up buried in a gorge. With no one to help them, they realize they can trust the dragons to save them, but the farm animals are still too fearful. The trainers try to teach the animals to trust the dragons, however in the end it is the dragon's natural protective instincts that are key.
With vikings and dragons now at peace, Gobber's role as weaponsmith is no longer needed. Hiccup tries to find him a new job.
In the aftermath of the events of the movie, the kids are enjoying their new lives with dragons, but the rest of the villagers aren't so sure. Hiccup and his friends have to find a way to train the dragons to live in peace with the rest of Berk.
During Snoggletog (the winter holiday), the dragons leave Berk and Hiccup must find out why. Since Toothless can't fly without a rider, he can't leave until Hiccup builds him a new tail.