The Pack - Saulness E.C.

Burned-out private detective, Frank Shepard, has a dangerous secret that has followed him for nearly a century. He's a werewolf. A curse that has cost him everyone he loves. In another life he was a soldier, a brother, and a husband. Now he lives in a run-down trailer on the edge of town and drowns decades of traumatic memories in alcohol and opiates.

That is, until his old partner-the only one who knows about Frank's werewolf nature-calls in old debts for help on a missing person's case. Unable to refuse, Frank is forced to leave his self-imposed isolation to join the hunt. A job that quickly entangles him in a web of revenge, murder, ghosts, and fey creatures in a dark supernatural underworld. In which Frank increasingly feels that he may be the worst monster of them all...