An evil troll (called the "devil") has made a magic mirror that distorts the appearance of everything it reflects. It fails to reflect the good and beautiful aspects of people and things, while magnifying their bad and ugly aspects. The devil, who teaches a "devil school," took the mirror and his pupils throughout the world and delight in using it to distort everyone and everything; the mirror makes the loveliest landscapes look like "boiled spinach." They tried to carry the mirror into Heaven with the idea of making fools of the angels and God, but the higher they lifted it, the more the mirror grinned and shook with delight, and it slipped from their grasp and fell back to earth, shattering into millions of pieces. These splinters — some no larger than a grain of sand — were blown around and get into people's hearts and eyes, freezing their hearts like blocks of ice and making their eyes like the troll-mirror itself, seeing only the bad and ugly in people and things.
Years later, a little girl, Gerda, and a little boy, Kai, live next door to each other in the garrets of buildings with adjoining roofs in a large city. One could get from Gerda's to Kai's home just by stepping over the gutters of each building. The two families grow vegetables and roses in window boxes placed on the gutters. Gerda and Kai have a window-box garden to play in, and they become devoted to each other as playmates.
Kai's grandmother tells the children about the Snow Queen, who is ruler over the "snow bees" — snowflakes that look like bees. As bees have a queen, so do the snow bees, and she is seen where the snowflakes cluster the most. Looking out of his frosted window one winter, Kai sees the Snow Queen, who beckons him to come with her. Kai draws back in fear from the window.
By the following spring, Gerda has learned a song that she sings to Kai: Where the roses deck the flowery vale, there, infant Jesus thee we hail! Because roses adorn the window box garden, the sight of roses always reminds Gerda of her love for Kai.
On a pleasant summer day, splinters of the troll-mirror get into Kai's heart and eyes while he and Gerda are looking at a picture book in their window-box garden. Kai becomes cruel and aggressive. He destroys their window-box garden, he makes fun of his grandmother, and he no longer cares about Gerda, since all of them now appear bad and ugly to him. The only beautiful and perfect things to him now are the tiny snowflakes that he sees through a magnifying glass.
The following winter, Kai goes out with his sled to play in the snowy market square and — as was the custom — hitches it to a curious white sleigh carriage, driven by the Snow Queen, who appears as a woman in a white fur-coat. Outside the city she reveals herself to Kai and kisses him twice: once to numb him from the cold, and a second time to make him forget about Gerda and his family; a third kiss would kill him. She takes Kai in her sleigh to her palace, the people of the city decide that Kai died in the nearby river. Gerda, heartbroken, goes out to look for him and questions everyone and everything about Kai's whereabouts. She offers her new red shoes to the river in exchange for Kai; by not taking the gift at first, the river lets her know that Kai did not drown. Gerda next visits an old sorceress with a beautiful garden of eternal summer. The sorceress wants Gerda to stay with her forever, so she causes Gerda to forget all about Kai, and causes all the roses in her garden to sink beneath the earth, since she knows that the sight of them will remind Gerda of her friend. Gerda's warm tears raise one bush above the ground, and it tells her that it could see all the dead while it was under the earth, and Kai is not among them. Gerda flees and meets a crow, who tells her that Kai is in the princess's palace. Gerda goes to the palace and meets the princess and the prince, who is not Kai, but looks like him. Gerda tells them her story, and they provide her with warm clothes and a beautiful coach. While traveling in the coach Gerda is captured by robbers and brought to their castle, where she befriends a little robber girl, whose pet doves tell her that they saw Kai when he was carried away by the Snow Queen in the direction of Lapland. The captive reindeer Bae tells her that he knows how to get to Lapland since it is his home.