When Eustace Scrubb and Jill Pole arrive in Narnia in The Silver Chair, Prince Rilian (the only son of the now elderly King Caspian) has been missing for ten years.

When Eustace and Jill reach Cair Paravel, they learn that Caspian has embarked on a voyage to "see again the places of his youth" – but many believe that he has gone to ask Aslan who the next King of Narnia should be, as he fears he will never see his son again.

Eustace and Jill meet Puddleglum, a marsh-wiggle, and the three seek Rilian to the north in the land of giants.

Eventually they find their way underground to the Shallow Lands ruled by the Lady of the Green Kirtle, where they meet the black knight again.

After destroying the chair with his sword, he then reveals that he is Prince Rilian, and informs them of how the Lady kept him prisoner underground, enchanted by day and returning to sanity only at night.