In the summer of 1940, Peter, Susan, Edmund and Lucy Pevensie are evacuated from London to the countryside to live at the grand country house of Professor Digory Kirke.

The siblings explore the house soon after their arrival. Lucy looks inside a wardrobe in a spare room. On entering it, she finds herself in the snowy land of Narnia. She meets a kind faun called Mr. Tumnus and goes to have tea in his cave. However, Mr. Tumnus soon reveals to Lucy that he is employed by the White Witch, who rules Narnia and has made it always winter but never Christmas. He has received orders from the White Witch that if he ever sees a human in Narnia, he must hand them over to her. The faun realises he cannot go ahead with this, and at his own risk, shows Lucy the way home.

Lucy returns home and tells her siblings about Narnia but they find nothing when they look in the wardrobe, leading them to believe she is having a joke with them. Susan tries to persuade Lucy to admit that she made up the story about the wardrobe for fun, but Edmund has a spiteful and sarcastic approach towards his younger sister.

A few days later, during a game of hide and seek, Edmund follows Lucy into the wardrobe and finds out for himself that her story was true.

The lady introduces herself as the Queen of Narnia. When she learns Edmund is a son of Adam (human), she shows great kindness towards him, giving him a hot drink and turkish delight. In conversation, she learns that he has three siblings (a brother and two sisters), and that one of them has already been in Narnia and met a faun. The Queen seems rather alarmed when she hears about all of this. Edmund agrees to bring his siblings to meet the Queen, tempted by the offer of more turkish delight and the chance to be king of Narnia. The Queen then departs and Edmund makes his way back towards the lamp post.

Lucy then excitedly appears and tells Edmund that she has been back to see Mr. Tumnus, and that the White Witch has done nothing to him for letting her go. Lucy then describes the White Witch’s appearance, and Edmund realises that she is no other than the “Queen of Narnia” he has just befriended, but does not mention that he has met her. Lucy tells Peter and Susan that she has been back in Narnia and that Edmund has also been there, but Edmund lies by saying that he and Lucy were playing a game, angering Peter and Susan - who still disbelieve Lucy, but are angry with Edmund for playing along with her story. The professor, however, attempts to convince them that Lucy could be telling the truth, after they mention that Lucy had always been the more truthful of the two siblings, and he dismisses the suggestion that Lucy might be suffering from madness. Peter later tells Edmund put a stop to his behaviour towards Lucy, while Susan adds that they should all keep away from the spare room and the wardrobe.

Lucy convinces her siblings to try and save Mr. Tumnus, feeling responsible for his arrest. They move on from the cave, not knowing exactly which direction to head in. The children soon encounter Mr. Beaver, who proves to be an ally. He takes them to his dam where he and his wife provide them with dinner.

They inform them that Mr. Tumnus was captured by the secret police, who were last seen taking him in the direction of the Witch's castle, where few people taken inside have ever come out again - the majority have been turned to stone. The beavers also give the children information about Aslan the lion, the true king of Narnia who is returning to Narnia to bring about the demise of the White Witch. The children learn they are part of a prophecy which states that two sons of Adam and two daughters of Eve will be crowned kings of Narnia, which will not only spell the end of the White Witch’s reign, but of her life.

Lucy suddenly notices that Edmund has disappeared. Mr. Beaver informs them that there is no point in going to search for Edmund, as they already know where he’s gone - to the White Witch, having allied himself with her on his previous visit. Mr. Beaver had noticed a look in Edmund’s eyes when he first laid eyes on him, which signalled that he had met the Witch and eaten her food, and been told where she lived. The beavers realise the Witch will set out to catch them that very night, and prepare for their journey to the stone table to seek help from Aslan.

The beavers and the three other children get ready for their journey, while Edmund waits with the Witch as a dwarf prepares their sleigh ready for their own journey.

The Witch sends Maugrim, to kill Edmund's siblings and the beavers. However, when Maugrim and another wolf arrive, they find the children and the beavers have already left, so make their way to the stone table, as instructed by the Witch. The harshness of the Witch’s winter mean that Maugrim has no tracks to follow, and the scent is cold. The two wolves then leave to make their journey to the Stone Table.

The beavers and the children make their journey through the snow, careful to stick to routes where the Witch’s sleigh would be unable to travel, and eventually reach a hiding place for a night’s rest.

The next morning, the beavers and the children are awoken by the sound of jingling bells, which they mistake for the Witch’s sleigh. Mr Beaver creeps out of the hiding place to investigate, and instead is greeted by Father Christmas - a fresh sign that the Witch's magic is weakening. Peter receives a sword and shield to fight in the battle. Susan is given a horn to call for help when in danger. Lucy is given a dagger and a cordial to heal any wound.

Meanwhile, Edmund and the Witch have journeyed through the night, and in the morning they encounter a party of Narnian creatures enjoying a feast. The Witch is horrified to learn that Father Christmas has been in Narnia, and turns the creatures into stone. Edmund had already realised that he had allied with the wrong side, but this event makes him realise the full extent of the Witch’s evil.

The children and the beavers are welcomed at the stone table by Aslan and his followers (mostly dryads, dwarves and fauns). Aslan agrees to help save Edmund when he learns of his betrayal.

Aslan then shows Peter a far off sight of Cair Paravel, where he is to reign as High King. Maugrim then appears and Peter slays him, being knighted by Aslan. Six of Aslan's followers (an animated pegasus, griffin, flying puma, cockatrice, eagle, and pelican) pursue the Witch’s surviving wolf to save Edmund which they do just as the Witch is about to kill him (to prevent the prophecy of Cair Paravel).

Edmund reaches the Stone Table and, following a conversation with Aslan, apologises to his siblings for his mistakes. The Witch later arrives and demands her right to kill Edmund as all traitors belong to her, according to the deep magic. However, in a private conversation, Aslan persuades her to renounce her claim.

Susan and Lucy spend the night by Aslan's body. The next morning, the stone table cracks and Aslan reveals he is alive and well, much to the relief of Susan and Lucy. Aslan tells them he was saved by a deeper magic which the Witch did not know: when a willing victim who has committed no treachery is killed in place of a traitor, death will work backwards, thus the victim’s life will be restored.

Aslan brings Susan and Lucy to the Witch's castle where he restores all of the Narnians she had turned to stone, including Mr. Tumnus. They flee the castle and head for the battlefield. Meanwhile at the battle, the Witch has been turning many of Aslan’s followers into stone, but Edmund brings down his sword on the Witch's wand, although she wounds him with the remains of it. Aslan arrives with the Narnians he saved, and kills the Witch. Most of her followers are wiped out and the surviving villains flee, just after Aslan and the freed Narnians arrive.

Edmund and the others injured in the battle are restored by Lucy's cordial. The next day, Aslan brings his followers to Cair Paravel where he crowns the Pevensies as rulers of Narnia. He then leaves, much to the sadness of the Pevensies. Mr. Beaver comforts them by assuring that Aslan will come and go as he has other countries to attend to.