Faceless: The Last Mage Book 5. The Last Mage, #5

Carter Nash, the Last Mage, has been traveling between dimensions for quite a while with a few of his allies from his home in McLain, Mississippi. However, he finds himself in the much smaller town of Enterprise, Mississippi and he is immediately recognized, but he doesn't know anyone. The town is completely unfamiliar to him. He soon finds his way around and learns that there was another person there named Carter Nash that claimed to be a private investigator while few knew him as a Mage.
Carter believes he has switched places with this person and is soon called into service as an investigator to locate a missing school teacher. Before he can locate this person, he is also brought into a situation involving a ghost haunting a fairly new house. As the investigations progress rapidly, the two cases become intertwined and bring to light a large evil presence in the town. It's up to Carter to learn the truth and resolve these issues before he can attempt to return home.