McRae, Murder at the Opera. The McRae Series

San Francisco, 1906. Broderick McRae, reporter for the Morning Call, has discovered he's two people. A different person inhabits his mind and body. The Other is a dead Italian soldier named Abramo. He tells McRae they are both on a mission to save the city. Their task involves a murdered opera singer and a killer on the loose. There's also Enrico Caruso, who's coming to town. McRae doesn't even like opera.
Worse yet, McRae's dear wife Julianna has just left him. After all this, things start getting complicated.