Just when Jill, Eustace and Puddleglum think there is no place lower than Underland they find out how wrong they were.
In The Silver Chair our friends become trapped while trying to rescue the lost prince. They find Gnomes, or Earthmen who are under the spell of the Lady of the Green Kirtle. She rules Underland and is planning to use Prince Rilian as a slave-king to take over Narnia.