The Hour of the Dragon

Conan has become king of Aquilonia and, despite his history of wanderlust, proves to be a steady, compassionate, and just king. When the evil power of the ancient wizard Xaltotun is unleashed upon his kingdom, Conan is forced to go into hiding and pursue the magical gem responsible for reviving the long-dead Xaltotun, and necessary to defeat the vile sorcerer.
Conan, loses and regains a kingdom through lands of mystery and enchantment as he fights this evil sorcerer from the mythical past.

This book is the only novel that Robert E. Howard, the creator of Conan, wrote, and also the only full length novel that he ever completed.