The four Pevensie children—Peter, Susan, Edmund, and Lucy—are evacuated to the country house of a professor during the Blitz. There they discover a magic wardrobe that allows them to pass into Narnia, a world inhabited by talking animals and ruled by the White Witch. Since coming into power, the Witch has held Narnia in an eternal winter, never permitting Christmas or spring; all of Narnia has been waiting for the return of Aslan, the Lion and Lord of Narnia, to overcome the Witch and reawaken the land. Lucy befriends a faun, Mr. Tumnus, who is summarily arrested by the Witch for conspiring with a human; unbeknownst to the children, she has demanded that any humans be brought to her at once, for there is a prophecy that when four humans take the empty thrones at Cair Paravel, evil will be banished from Narnia.
Edmund is seduced by the Witch’s offer of power and tricked into betraying his siblings; the other three, befriended by a kindly Beaver couple, escape to meet the newly-returned Aslan. The Witch pursues them, but when she discovers that they have already met with Aslan she decides to kill Edmund, thus ruining the prophecy. At the last moment Edmund is rescued, and after speaking with Aslan is forgiven his behavior.
The Witch, however, has another plan, and demands the death of Edmund as a traitor to his family, for it is part of the Deep Magic of Narnia that all traitors are her prey; after much discussion, Aslan offers himself instead. In doing so, however, he tricks the Witch; so eager is she to kill him that she does not realize she will be spilling innocent blood in place of a traitor’s, and that it is part of deeper magic that to do so will break her power and cause death itself to reverse. Thus Susan and Lucy, caring for the body of Aslan, soon find that he is not dead but reborn,. He returns to the battle now raging between his army and the Witch’s and kills her. Peter, Susan, Edmund, and Lucy take their rightful thrones at Cair Paravel, and rule in peace for decades.
Until one day when they are hunting the White Stag, and find themselves at the entrance to the wardrobe once more. Just as they first explored it as children, so now, with no memory of their past, they decide to explore this strange entrance to another world . . . and find themselves back in the house of the professor, back at the time and age of when they first entered Narnia. The professor, who has had his own experiences at Narnia, explains that they will not be able to use the wardrobe again, but they will be called back to Narnia by a different route, for another adventure to come.