The Evening before Hiccup is taken to be with the dragons, King Agnarr of Arendelle tells a story to his children, Elsa, Hiccup and Anna.
That their grandfather, King Runeard, had established a treaty with a neighboring tribe of Northuldra and a ancient dragon, known as the Foreverwing.
By building a dam in their homeland, the Enchanted Forest, this dam would strengthen their waters.
However, a fight occurs, resulting in Runeard's death, the fight engages the Foreverwing and the elemental spirits of Earth, Fire, Water, and Air of the forest.
The spirits and the Foreverwing disappear, by placing a wall of mist that traps everyone in the Enchanted Forest.
The young Prince Agnarr barely escapes due to the help of an unknown saviour, as a the roar of the Foreverwing and a magical siren echo across the land.
Three years after her coronation and the return of Hiccup, Arrendale celebrates the autumn harvest in the kingdom with Anna, Olaf, Kristoff, Sven, and the dragons.
After the harvest, when the group is playing charades, Elsa hears the magical siren and Hiccup starts to hear the Foreverwing's call.
The two of them follow their magical instincts, but accidentally awaken the spirits and the ancient dragon, forcing everyone in Arrendale to evacuate.
When the Kingdom regroups and Anna finds out why her sister and Hiccup had been so quiet, Grandpabbie and the Bewilderbeast inform them that they must travel north to find the truth about the past.
When they reach the massive wall of mist, Hiccup and Elsa part it with their touch and the group adventure into the Unknown.
When memories and old faces are shown to the Ice Queen and Dragon Prince, the full story of why the forest was concealed is revealed.
Find out what happens in the final chapter of Snow and Fire, as the truth
When one-month-old orphaned boy Hiccup Haddock is brought before the King and Queen of Arrendale, they take him in and act as his parents.
During this time the Iduna and Agnar discover that he is the prophesied Dragon Prince, that will one day unite the dragon and human worlds to become the King of dragons.
Five years go by and the young Princess Elsa, her brother Prince Hiccup and younger sister Princess Anna have developed an unbreakable bond.
The elder siblings possess magical powers that allow them to control and create snow and fire, often using them to play with Anna.
One night, when the children sneak down to the ballroom, Elsa accidentally injures Anna with her magic and Hiccup begins to experience shifts in his abilities.
The King and Queen, take the children to a colony of trolls led by Grand Pabbie, he heals Anna, by altering her memories of the magical children.
Grand Pabbiee warns Elsa that she must learn to control her magic, that if she fears it, that fear will become her greatest enemy.
The ancient Troll further informs the King and Queen that it is time for Hiccup to go with the dragons.
The dragons arrive, led by the Fireworm Queen and the royal family say their goodbye's, Elsa is particularly saddened that she will never get to see Hiccup again.
Agnar and Iduna isolate Elsa and Anna within the castle, closing the gates to their subjects, in an effort to protect their daughter from hurting herself and others.
Elsa ceases all contact with Anna, tearing a rift between them and their bond.
Hiccup, however, grows up in the freedom of adventure and a family of dragons, his life is far from the one he had with the royal family.
Agnar and Iduna set out on a joint journey to find their lost son and the answer to Elsa's powers, but are lost at sea during a fierce storm.
Elsa is crowned Queen, but within the congregation is her long lost Hiccup, who heard of her crowning.
What will happen when the two meet again, will love thaw Elsa's frozen heart?