The Knight is really a Prince, who has been stolen from his home and placed under an enchantment by the lady in
the strange, green dress. She intends to use him to lead an attack on his homeland. Each night the enchantment lifts and the Prince is tied to a magic chair. When he is eventually rescued, the lady turns into a serpent and attacks him. Fortunately, there is a happy ending as this is Narnia and not Montecito.
Apologies if this comes out a complete mess!