The Detective and the Mirror. Shadows of Coal, #5

What happens when the mirror looks back?Thomas Kane has spent years hunting the Gray Brotherhood, but now the hunt has turned inward. A new killer is stalking the streets of the Coal District-a killer who knows Thomas's methods, mimics his signature, and wears his face. Framed for a series of brutal murders and suspended from the force, Thomas is forced to go on the run. But he isn't just running from the police; he is running from the terrifying possibility that he may be the killer.
As the evidence mounts and his own memories begin to fracture, Thomas uncovers the existence of Project Mirror: a decades-old experiment designed to fracture the human consciousness into perfect opposites. Hunted by his own department and taunted by a doppelgänger who claims to be his true self, Thomas must confront the darkest question of his life: Is he the detective seeking justice, or is he merely the shadow designed to hide the monster?In this psychological descent into madness, Thomas Kane must destroy his reflection before it destroys him.