Dark World Series by T.G. Ayer

Panther Shape-shifter Kailin Odel just wants to be normal. Leaving her clan, and her Alpha responsibilities, to live with her grandmother in Chicago had been the best thing for her. Only then did she discover her ability to track and kill the soul sucking undead creatures called Wraiths. Now she protected the humans, and had something to be proud of... morePanther Shape-shifter Kailin Odel just wants to be normal. Leaving her clan, and her Alpha responsibilities, to live with her grandmother in Chicago had been the best thing for her. Only then did she discover her ability to track and kill the soul sucking undead creatures called Wraiths. Now she protected the humans, and had something to be proud of. But, when she discovers the body of a murdered shape shifter, Kailin has to come to terms with the reality that her own kind are just as vulnerable as the humans. The closer Kailin gets to the killer the more she has to face the intricacies of her people. When the time comes can she accept who and what her real purpose is? less

With her sister missing and her mother and Anjelo stuck in the Wraith World, Kai must find a way to save them all. But the Wraith poison has brought her to her knees and only Logan's fire can help ease her pain. Uncertain who to rescue first, Kai's decision is made for her when she discovers her sister Greer is stuck in the Greylands and slowly going insane... moreWith her sister missing and her mother and Anjelo stuck in the Wraith World, Kai must find a way to save them all. But the Wraith poison has brought her to her knees and only Logan's fire can help ease her pain. Uncertain who to rescue first, Kai's decision is made for her when she discovers her sister Greer is stuck in the Greylands and slowly going insane. Desperate to save her, Kai will go to incredible lengths to obtain a portal key to the land of the dead - and maybe, she’ll go one step too far. From Death-talkers to demons, trackers to ghosts, Kai must fight against betrayal and evade the clutches of danger to set her sister free. Can she save Greer from a horrific death - and will she ever be able to forgive herself if she can’t? ++Warning: Mature reader recommendation- this book contains violence less