The Silver Chair completes the Caspian trilogy within "The Chronicles of Narnia," begun with Prince Caspian and continued in The Voyage of the "Dawn Treader." In The Silver Chair, Caspian is old and in failing health, soon to die. More than ten years earlier his wife, the daughter of the retired star Ramandu, was killed by a serpent and then his son Rilian disappeared, apparently kidnapped by a mysterious, magical woman dressed in green. Many of Narnia's greatest heroes have set out in search of the prince, but have never returned, so Caspian eventually decreed that no one shall search for his son, in order to prevent the loss of more good Narnians. Having heard that Asian has been seen in the Lone Islands, Caspian himself prepares for one last voyage in the hope that Asian will find Rilian.

In the meantime, Jill Pole has her own problems at a school named Experiment House. It is the latest in progressive education in which the staff takes care that bullies and thugs don't have their psyches damaged by any kind of discipline. Indeed, the beating up of children seems to be encouraged by the faculty. When Jill hides from a gang that wants to beat her up, she is unexpectedly helped by Eustace Scrubb. This is unexpected because Eustace had once been a monster, cruel and vicious, but he has changed into a more compassionate person. At his urging, Jill and he call to Asian and are transported to another world.