Sleutherian

After death, humans become creatures called Sleuthers until they can get out of purgatory. However, in order to leave purgatory, one must first kill a living human and use their soul for safe passage to the spirit world. If the soul a Sleuther takes is grieved before the Sleuther can get to the spirit world, the Sleuther becomes trapped in purgatory once more. When one human refuses to let go of the pain that comes with loosing loved ones, Alenuo, a Sleuther, must get her to stop mourning in order to protect the future of humanity, and unlock the secrets of escaping purgatory.