The very first (chronologically) Narnia story. It tells the story of Digory, Polly, and the birth of Narnia.
Digory has recently moved to London to live with his Aunt and Uncle because his mother is ill. He soon meets Polly and they begin having adventures in the crawl spaces in their houses. Soon, however, they come across Uncle Andrew who announces he is a magician and tricks Polly into touching a magic ring and she vanishes. Digory follows to rescue her.
They find themselves in a strange wood with trees so tall their tops are out of sight and strange pools of water everywhere. Using the rings to try and get home they find themselves on a strange world with a bright red sun and run into Janis, an evil Queen, who has destroyed her world and people.
They accidentally bring her back to our world where she causes havoc and in an attempt to get rid of her the children come into a strange world where there is nothing but music. Things like trees and animals begin to emerge from the ground... And a very strern and stately lion gives Digory a mission that if successful could save his mother.