Nightspell (Mistwood #2) by Leah Cypess
A stand-alone companion novel to the much-acclaimed MISTWOOD. When Darri rides into Ghostland, a country where the living walk with the dead, she has only one goal: to rescue her younger sister Callie, who was sent to Ghostland as a hostage four years ago. But Callie has changed in those four years, and now has secrets of her own. In her quest to save her sister from herself, Darri will be forced to outmaneuver a handsome ghost prince, an ancient sorcerer, and a manipulative tribal warrior (who happens to be her brother). When Darri discovers the source of the spell that has kept the dead in Ghostland chained to this earth, she faces a decision that will force her to reexamine beliefs she has never before questioned – and lead her into the heart of a conspiracy that threatens the very balance of power between the living and the dead.