The Silver Chair

The Silver Chair is the fourth published book in 'The Chronicles of Narnia' series.

It follows Eustace Scrubb, who returns to Narnia along with his classmate Jill Pole, on a mission from Aslan to find Prince Rilian, the son of King Caspian.

The story involves their journey through the underground world of Narnia, facing various dangers and encountering the Lady of the Green Kirtle, who has enchanted Prince Rilian.

With the help of Puddleglum the Marsh-wiggle, they manage to break the curse and free Rilian, leading to the defeat of the Lady of the Green Kirtle and the return of Rilian to his father's kingdom.