Princess Elsa of Arendelle discovers she has control over ice and snow at a young age. However, upon injuring her younger sister Anna with her powers, their parents bring her to a clan of trolls, who heal Anna's wounds, but also erase her memories of Elsa's powers. To keep the two princesses safe from harm, the King and Queen keep the two sisters isolated from each other. Years later, when the two sisters are teenagers, the King and Queen die at sea. Three years after the tragedy, Elsa is to be crowned queen of Arendelle. Among those visiting is the greedy Duke of Weselton, ice harvester Kristoff, and Prince Hans of the Southern Isles, who Anna becomes smitten with.
The coronation goes off without incident, but at the subsequent celebration party, Hans proposes to Anna, who hastily accepts. Elsa refuses to give the two their blessing, leading to an argument in which Elsa's powers are exposed. Labelled a monster by the Duke, Elsa flees the kingdom and unintentionally unleashes an eternal winter upon the kingdom. Anna, blaming herself for the curse, sets off to find her sister and undo the curse. Meanwhile, Elsa arrives into the mountains and decides to live a solitary life, declaring herself free to express her powers. She encounters Kristoff and his reindeer Sven on her quest at Oaken's trading post, who guides her to the mountains. However, on their journey through the forest, they are attacked by a pack of wolves. Though the three escape unharmed, Kristoff's sled is destroyed, forcing them to travel on foot. Meanwhile, Hans leads a search party towards the mountains to retrieve Anna and Elsa, unaware that the Duke has ordered his men to kill Elsa.
Anna, Kristoff, and Sven encounter an snow golem named Olaf, who had been created by Elsa. Olaf guides them to Elsa's ice palace, where Anna appeals to Elsa to return to Arendelle and undo the curse. Elsa becomes agitated and loses control of her powers, unintentionally striking Anna in the heart. Horrified, Elsa creates a snow golem named Marshmallow, who throws the trio out of the palace. After Anna provokes Marshmallow, he pursues them through the forest, culminating in the group plummeting off a mountain. The group survives, but Kristoff notices that Anna's hair is turning white and realizes that it is a result of Anna being struck by Elsa. Kristoff takes Anna to the trolls, who explain that Anna will freeze solid unless the curse is broken by an act of true love. Believing Hans can save Anna, Kristoff journeys to return her to Arendelle.
Hans' searching party arrives in the mountains and are attacked by Marshmallow, but Hans severs his leg, causing him to fall into a chasm. The Duke's men infiltrate the palace and, in the ensuing confrontation, Elsa is knocked unconscious and returned to Arendelle. Hans pleads for Elsa to undo the curse, but she explains that she cannot. Shortly afterwards, Anna is returned to the kingdom by Kristoff and Sven, who then return to the forest. Anna pleads for Hans to kiss her, but he refuses, revealing his true intentions of ruling Arendelle. Abandoning Anna to die, Hans tells the dignitaries that Anna has perished and sentences Elsa to death for treason. However, Elsa manages to escape her confines and flees onto the fjord, unleashing a blizzard that engulfs the kingdom. Kristoff and Sven, noticing the blizzard, return to the kingdom to rescue Anna.
Olaf finds a weakened Anna and reveals that Kristoff loves her. The two escape the castle and journey through the blizzard to find Kristoff. At the same time, Hans locates Elsa within the blizzard and tells her that Anna has died, leaving Elsa heartbroken. In her despair, she causes the blizzard to subside, allowing Anna and Kristoff to reach each other. However, Anna notices Hans about to kill Elsa and rushes to save her sister, intercepting Hans' blow. Anna freezes solid just as Hans strikes her, which knocks him unconscious. Elsa mourns Anna's demise, but she thaws immediately afterwards, as her sacrifice for her sister constitutes as an act of true love. Elsa, realizing love is the key to controlling her powers, successfully undoes the curse over the land.
Hans is shipped back to his country to receive punishment for his actions while Elsa cuts off trade with Weselton in retribution for the Duke's crimes against her. Kristoff, Olaf and Sven remain in Arendelle, and Kristoff becomes Anna's fiancé. Elsa reconciles with Anna as well, and the two become closer than they were before.
- Kristen Bell as Princess Anna of Arendelle.
- Idina Menzel as Elsa the Snow Queen.
- Jonathan Groff as Kristoff Bjorgman.
- Josh Gad as Olaf.
- Santino Fontana as Prince Hans of the Southern Isles.
- Alan Tudyk as the Duke of Weselton.
- Ciaran Hinds as Grand Pabbie
- Chris Williams as Oaken.
- Stephen J. Anderson as Kai.
- Maia Wilson as Bulda.
- Edie McClurg as Gerda.
- Robert Pine as the Bishop of Arendelle.
- Maurice LaMarche as the King of Arendelle.
- Jennifer Lee as the Queen of Arendelle.
- Jesse Corti as Spanish Dignitary.
- Jeffrey Marcus as German Dignitary.
- Tucker Gilmore as Irish Dignitary.