Derek Strange and Terry Quinn mysteries

"Washington, D.C., 1972. Derek Strange has left the police department and set up shop as a private investigator. His former partner, Frank "Hound Dog" Vaughn, is still on the force. When a young woman comes to Strange asking for his help recovering a cheap ring she claims has sentimental value, the case leads him onto Vaughn's turf, where a local drug addict's been murdered, shot point-blank in his apartment. Soon both men are on the trail of a ruthless...