Isle of Joy book by Don Winslow

"New York, late 1958. Walter Withers had given the best years of his life to the CIA ... But Withers has returned to his hometown ... as a private investigator. Manhattan in the late fifties is alive with new possibilities, new sounds and new faces, including young presidential hopeful Senator Joe Keneally. Withers is assigned to bodyguard Keneally's girlfriend as a society gathering ... But next morning, sh'es dead - and Withers is the prime suspect. To clear his name Withers must take on his old masters from the CIA, as well as J. Edgar Hoover's FBI, all of them determined to set Keneally up. And Withers ... becomes another disposable victim of the trap closing in on the Senator. Published By Random House on 1996