This Wicked City by Michael Walsh

Crime and corruption are rising in Ocean Park, a tired factory town in northern Massachusetts. The police and fire departments are no help—they're staging a work slowdown to protest a pay freeze caused by city budget cuts. Police Detective Matt Conley is disgusted with the dereliction of duty, and when tasked with solving the murder of a young Haitian immigrant, he infuriates the force by teaming with the victim's friend Emmanuel to find the killer. They encounter an enterprising family of Voudou worshipers, a ruthless real estate magnate, and a clever, love-struck arsonist in their search for justice. This Wicked City is a mystery powered by its characters' struggles with love, loyalty, and sacrifice.