The Sorcerer King by Frewin Jones

Tania has brought the long-lost Queen Titania back to Faerie from the Mortal World of modern London. But when they cross between the worlds, they find only devastation.

The Sorcerer King of Lyonesse -- ancient enemy of the Faerie Court -- has been released from his amber prison. As the wicked sorcerer regains his power, King Oberon, Tania's father, is imprisoned and the Faerie Court is being destroyed.

Tania and her true love, Edric, must travel the Realm to try to find and rescue King Oberon, who is their only hope for defeating the evil Sorcerer King. And Tania must prepare for battle . . . and to fight a war that she may not survive.