Which fictional location is featured in the children's novel published fourth in "The Chronicles of Narnia" series by C. S. Lewis?
Underland (Narnia): The Underland is a fictional location in the children's fantasy series "The Chronicles of Narnia" by C. S. Lewis. Underland (Narnia):  Described by Lewis as lying beneath the land of Narnia, Underland appears mainly in The Silver Chair, where Eustace Scrubb and Jill Pole travel under the ground to reach it in their search for Prince Rilian. The Silver Chair:  It was the fourth published of seven novels in "The Chronicles of Narnia" (1950–1956); it is volume six in recent editions, which are sequenced according to Narnian history.
Underland