Book Appearances: The Silver Chair
Movie Appearances: The Silver Chair (BBC)
Overview: The Silver Chair is the enchanted chair in Underland used by the Lady of the Green Kirtle to bind Prince Rilian and disguise the true nature of his captivity.
In the story
The chair matters because it makes enchantment look almost ceremonial. What appears regal or important is in fact part of a prison.
It also gives the book its title, which tells you how central this object is to the whole story.