The Lion, the Witch and the Wardrobe

The second book in the classic fantasy series, The Chronicles of Narnia.
 
Four adventurous siblings – Peter, Susan, Edmund, and Lucy Pevensie – step through a wardrobe door and into the land of Narnia, a land frozen in eternal winter and enslaved by the power of the White Witch. But when almost all hope is lost, the return of the Great Lion, Aslan, signals a great change... and a great sacrifice.