Plot

When Hiccup and Toothless discover an ice cave that is home to hundreds of new wild dragons and the mysterious Dragon Rider, the two friends find themselves at the center of a battle to protect the peace.

It's been five years since Hiccup and Toothless successfully united dragons and vikings on the island of Berk. While Astrid, Snotlout and the rest of the gang are challenging each other to dragon races (the island's new favorite contact sport), the now inseparable pair journey through the skies, charting unmapped territories and exploring new worlds. When one of their adventures leads to the discovery of a secret ice cave that is home to hundreds of new wild dragons and the mysterious Dragon Rider, the two friends find themselves at the center of a battle to protect the peace. Now, Hiccup and Toothless must unite to stand up for what they believe while recognizing that only together do they have the power to change the future of both men and dragons.—Twentieth Century Fox Film Corporation

Five years after Hiccup unified dragons and Vikings, they all face a new enemy - Drago, a man starting a war with dragons to rule the whole world once and for all. While Stoick would rather lock up and stay away from him, Hiccup wants to reason with him like he did with his dad. Traveling away from Berk, Hiccup comes across his long lost mother, who has been riding dragons way before he has. Does Hiccup have what it takes to take on Drago and his army of dragons?—James Hake

Five years after the events of How to Train Your Dragon (2010), Hiccup and Toothless have successfully united dragons and Vikings. However, as Stoick the Vast prepares to retire, selecting carefree Hiccup as the new chieftain of Berk, the unlikely hero has to face his biggest challenge: confront legendary warlord Drago, a ruthless hunter bent on capturing all dragons to take over the world. And now, there is no turning back. Can Hiccup and Toothless stand against Drago's army to protect the peace?—Nick Riganas

A group of young vikings discover new and incredible dragons including the king of dragons as they are doing everything that they possibly can to defeat an enemy. They must protect all of the dragons with the help of a relative who has returned.—RECB3

Five years after the Viking village of Berk has made peace with the dragons, dragons now live among the villagers as working animals and companions and even take part in racing sport. Dragons and their riders compete to catch sheep and dunk them in baskets. Everyone in the village who isn't competing seems to be watching the event. Berk now has custom stables for the dragons, including all you can eat feeding stations, a full-service dragon wash, and advanced fire prevention systems. Astrid and her dragon Stormfly (a Deadly Nadder) win the game, and Stoick calls Astrid his future daughter-in-law.

Hiccup Horrendous Haddock III (Jay Baruchel) goes on adventures with his dragon, Toothless (Randy Thom), as they discover and map unexplored lands and territories. Hiccup discovers new islands far away from Berk and maps them on a document that he maintains in his diary. Hiccup tries out a set of leather wings he's rigged that stretch from his extended arms to the sides of his legs and enable him to jump off Toothless' back and fly. Hiccup is found by Astrid on the new Island where they have a conversation. Hiccup says that, having come of age, he is being pressed by his father, Stoick the Vast (Gerard Butler), to succeed him as chieftain, although Hiccup remains unsure if he is ready for this responsibility. Astrid believes that becoming a chief is a huge responsibility and a honor.

While investigating a wildfire on a recently discovered Island, Hiccup and Astrid (America Ferrera) discover the remains of a fort encased in a colossal ice formation and encounter a dragon trapper named Eret (Kit Harington), who blames them for the destruction of his fort. He says the fort was frozen and destroyed by another dragon rider who he assumes they are in league with. Eret says that destruction of the fort makes his job of catching dragons that much more difficult.

Eret attempts to capture their dragons for an insane conqueror called Drago Bludvist (Djimon Hounsou). Drago is a ruthless warlord and dragon hunter who seeks to take over the world with a dragon army. Hiccup and Astrid are mystified as they have never heard of dragon riders except for the ones from Berk.

Eret attempts to capture Stormfly and Toothless, but Hiccup and Toothless launch a counterattack and manage to escape from Eret and his goons.

The two riders return to Berk to warn Stoick about the dragon army that Drago is amassing, and Stoick orders the villagers to fortify the island and prepare for battle. Stoick explains that he once met Drago at a chieftain gathering, where Drago offered them protection from dragons if they pledged to serve him. Upon denying him, he had his dragons attack them, leaving Stoick as the sole survivor. But Hiccup refuses to believe that war is inevitable and flies off with Toothless to find Drago and to talk some sense into him.

Hiccup and Astrid surrender themselves and their dragons to Eret so as to be taken to Drago. Hiccup says that he is determined to change Drago perception about Dragons. Hiccup says that once a human earns a dragon's trust, there is nothing that the dragon would not do for the human.

However, Stoick, Gobber (Craig Ferguson) Stoick's closest friend and a seasoned warrior, and Berk's other dragon riders pursue and find them on Eret's ship. Hiccup argues that if he could change Stoick's mind, he could change Drago's too. Hiccup and Toothless fly off again to evade Stoick.

They are captured by a dragon rider named Valka (Cate Blanchett), who is revealed to be Hiccup's long-lost mother. She explains that she had tried to convince Stoick and the rest of Berk that they could learn to coexist with dragons. One night, 20 years ago, during an attack, a dragon got into her house, and she rushed to save the infant Hiccup, but found the dragon, Cloudjumper, making googly eyes at the delighted baby. Though she had come armed and was fully prepared to put aside her ideas about the gentleness of dragons to defend her son, she couldn't bring herself to attack Cloudjumper, who instead carried her off.

Valka explains that, like her son, she couldn't bring herself to slay dragons. Instead, she rescues them from Drago and brings them to an island nest formed out of ice by a massive, ice-breathing alpha dragon called a Bewilderbeast, which can control smaller dragons by emitting hypnotic sound waves. Valka is eager to share what she's learned with Hiccup. She shows him and Toothless how to deploy a double row of small fins on Toothless's back that enable him to make tighter turns. Later, when Hiccup shows her the map he's been working on, adding new lands as he discovers them, she draws him a larger map in the snow.

Stoick tracks Hiccup to the island where he discovers that his wife is still alive. Simultaneously, Astrid and the other riders kidnap Eret to find Drago, but they are also captured, and Drago learns of Berk's dragons. Ruffnut (Kristen Wiig), a classmate of Hiccup and Astrid's from the dragon-fighting school, has a crush on Eret and pursues him doggedly, to the chagrin of Snotlout (Jonah Hill) and Fishlegs (Christopher Mintz-Plasse), who are both sweet on Ruffnut.

Upon learning of Berk's dragons, Drago directs his armada to attack the dragon nest. He also tries to execute Eret, but Astrid's dragon, Stormfly, saves him, prompting Eret to help the others escape.

Drago and his army lay siege to Valka's sanctuary, where he reveals that he has his own Bewilderbeast to challenge the Alpha. A titanic battle ensues between the two Bewilderbeasts in a fight for control over all dragons on the island. Drago's Bewilderbeast emerges victorious and seizes control of all the dragons, including Toothless. Hiccup urges Drago to cease violence, but Drago refuses, citing his family's death from dragon attacks in his childhood. He orders his Bewilderbeast to command Toothless to kill Hiccup.

Toothless, under the influence of the new Alpha, approaches Hiccup and fires a plasma blast. At the last instant, Stoick pushes Hiccup out of the way, and is hit instead, killing him instantly. Drago leaves Hiccup to his fate and, riding Toothless, leads his now larger army to destroy Berk. Stoick is given a ship burial and Hiccup and is now filled with regret at the loss of his father. Valka reminds him his father believed he could unite humans and dragons. Hiccup decides that he will fly back to Berk to defend his people and live up to his father's legacy.

The dragon riders ride baby dragons, which are immune to the Bewilderbeast's control, and arrive at Berk after the Alpha had already attacked the village and taken control of the dragons there. Hiccup confronts Drago and a brainwashed Toothless while the other riders work to distract the Bewilderbeast. Drago again orders Toothless to kill Hiccup, but Hiccup succeeds in disenchanting Toothless. Drago then orders the Alpha to shoot the pair, and the Bewilderbeast successfully encases them in a large blast of ice, seemingly killing them. His victory is short-lived, as Toothless, now glowing with plasma, blasts away the ice, revealing that both he and Hiccup are unharmed. Toothless enters a glowing, super-powered state, making him immune to the Bewilderbeast's control.

Toothless challenges the Alpha and repeatedly fires plasma blasts at the Bewilderbeast. This frees the other dragons from the Bewilderbeast's control and all fire at it, severely injuring the colossal dragon until Toothless fires a final massive blast, breaking its left tusk.

Defeated, Drago and his Bewilderbeast retreat into the ocean as the villagers celebrate their victory. All the dragons acknowledge Toothless as the new Alpha dragon, and Hiccup is made chief of Berk by the village elder. The film ends with Berk being rebuilt with a statue of Stoick erected in his honor, and Hiccup doing his duties as chief, proudly declaring that while others may have armies and armadas, Berk has its own dragons. Berk undergoes repairs, with Hiccup feeling confident that they will defend their peace with their dragons.