The Silver Chair (The Chronicles of Narnia #6) by C. S. Lewis

Through dangers untold and caverns deep and dark, a noble band of friends is sent to rescue a prince held captive. But their mission to Underland brings them face-to-face with an evil more beautiful and more deadly than they ever expected.

The Silver Chair is the sixth book in C. S. Lewis's classic fantasy series, which has been drawing readers of all ages into a magical land with unforgettable characters for over sixty years. This is a complete stand-alone read, but if you want to go farther into this magical land, read The Last Battle, the seventh and concluding book in The Chronicles of Narnia.