Murder by the Invisibles: Duke Becker, Book 4 (Unabridged‪)‬

Inspector Duke Becker and the Special Investigations Unit, Homicide, are down one man - Bobby Green is now on a medical retirement and working as a private investigator. He and Michelle Goldman can now have a real relationship, and things are looking up until a frightened conductor comes to see Green. Little does Green realize Becker and his squad will be investigating the same case, and together they will confront a mad cult, a martial arts killer, and numerous citizens of the Big Apple found killed along the way.

Along with a new detective known as Bing, a spiritual martial artist, Becker and his squad face something that could happen only in the streets of New York - and below them.