Max Allan Collins's Better Dead.

How could the CIA be in bed with the mob?  What lunacy is this?
--Max Allan Collins, Better Dead (Tom Doherty Associates, 2016).

This is the eighteenth in Collins's series about private detective Nate Heller.  These books vary somewhat in quality but, in general, they are impressive historical re-creations.  Heller gets involved with every thing from the Lindbergh kidnapping (Stolen Away, 1992) to the disappearance of Amelia Earhart. (Flying Blind,1999).  In Better Dead Heller is something of a double agent, working for Joseph McCarthy while reporting to Dashiell Hammett and investigating the death of scientist Frank Olson while trying to recover the CIA file on Joe McCarthy.

At various points I have studied the cases and their times that Heller investigates and Collins seamlessly integrates Heller with real people and places.  He perhaps is too influenced by Mickey Spillane -- every woman who meets Heller wants to sleep with him, including the "notorious" Bettie Page, and the violence is laid on rather thickly, though I enjoyed Heller punching out the slimy Roy Cohn in the men's room of The Stork Club for getting Frank Costello to sic his goons on Heller.  Heller brings the people and places of the 50's alive -- including Robert Kennedy, who worked for McCarthy's Senate committee --without significantly deviating from the facts.  Heller even has jailhouse interviews with Julius and Ethel Rosenberg who may have actually passed secrets to the Soviets but whose roles were exaggerated by prosecutor Roy Cohn, using faked evidence.

Collins includes a nicely detailed bibliography at the end for those interested.