King Agnarr of Arendelle tells his daughters Elsa and Anna that their grandfather, King Runeard, forged a treaty with the neighboring tribe of Northuldra by building a dam in the Enchanted Forest (their homeland). A fight occurs, however, resulting in Runeard’s death and enraging the forest’s classical elements of earth, fire, water, and air. The elements disappear, and a wall of mist traps everyone in the forest; Agnarr barely escapes, helped by an unknown savior.
Three years after her coronation, Elsa celebrates autumn in the kingdom with Anna, the snowman Olaf, the iceman Kristoff, and Kristoff’s reindeer Sven. One night, Elsa hears a mysterious voice calling her. She follows it, unintentionally awakening the elemental spirits and forcing everyone in the kingdom to evacuate.
The Rock Troll colony arrives, and Grand Pabbie tells them that Elsa and the others must set things right by uncovering the truth about the past. Elsa, Anna, Olaf, Kristoff and Sven follow the mysterious voice, and travel to the Enchanted Forest.
The mist parts at Elsa’s touch, while the air spirit appears as a tornado, catching everyone in its vortex before Elsa stops it by forming ice sculptures. She and Anna discover that the sculptures are images from their father’s past, and encounter the Northuldra and a troop of Arendellian soldiers who are still in conflict with one another.
When the fire spirit appears, Elsa discovers that it is an agitated magical salamander and calms it. Elsa and Anna arrange a truce between the soldiers and the Northuldra after discovering that their mother, Queen Iduna, was a Northuldran who had saved Agnarr (an Arendellian). They later learn about a fifth spirit, who will unite the people with the magic of nature.