The Silver Chair

Eustace Scrub and a girl are being chased by bullies. They wish for an entry in to Narnia. Then they go through a door and end up there. Narnia time has aged a generation since Eustace's last trip. He and the girl are supposed to go find the young prince to restore him to his thrown. Only, they don't communicate well and end up on a few detours before they go on their mission. They eventually strap a knight to a Silver Chair (hence the book's name) and manage to break an evil witch's spell and bring him back home.

This novel shows the gradual evolution of Scrub. He is still a little prick, but lets more of his good side show through. We also see the nefariousness of the witch, who manages to belittle everything with week comparisons. (When they say the sun is like a light, she belittles their world as being a mere imitation of her real world. Finally, they are able to overcome her be acknowledging that they would rather live in their potentially better world than be stuck in her 'known inferior' world.)

They also get their share of fantastical adventures, being blown by a lion's breath away from a miles high cliff, narrowly avoiding becoming the key ingredient in giants' meal, and finding an underground revolt.

This book is a pseudo-tangent. Read after Dawn Treader, it seems to flow fairly naturally. However, the story seems somewhat of a tangent from the main Narnia line (after all, Scrub was not introduced until the previous book). It also seemed to lack the engagement of the earlier books. However, it is still a fairly good story.