Full disclosure: I haven't read that many books on the subject but have always tended to believe it was a setup of some kind involving the mob and someone else. Principal reasons being Ruby's killing Oswald, and the murders of prime Mob suspects in 1975 during the Congressional investigation.
Now the review:
This book is painstakingly researched. The accumulation of detail makes for a difficult read for a while. It could have used an editor in the early chapters. For example, the minor figure Irving Davidson is introduced three times by his full name with a brief biographic sentence.
Toward the end, it really picks up speed. The week of the assassination reads quite well and conveys many convincing details.
The author - who teaches at the Naval War College - has apparently picked up the work of certain investigators on the 1970's Congressional investigation and I imagine they provided some direction to his efforts. They are cited in the book from time to time. The data in this volume, however, is not a pure rehash. It includes some recently declassified CIA documents. The evidence is utterly circumstantial, and there is of course no smoking gun or the book would have a lot more publicity. Every once in a while the author's speculation went past my threshold of credulity. I think he fails to recognize the healthy possibility that in the hysteria of the aftermath of the assassination there were many people who, like Catholics who convince themselves of apparitions of the Blessed Mother, convinced themselves of having seen Oswald or Ruby or that they heard someone make a veiled reference to plans for the assassination.
Midway through the book, I was losing confidence in my own beliefs as it didn't seem the details were adding up to anything at all. The author speculates Oswald may have been a double agent for the CIA - his pro-Castro public persona is suggested to be a cover for an attempt by someone, presumably the CIA, to introduce him into Cuba to shoot Castro. I didn't find that all that compelling as there is no rational explanation how he then goes off and shoots JFK.
Still, the details that come from more reliable sources, like telephone records, and so forth, eventually become compelling. And once Oswald goes to Mexico to attempt to obtain a visa for Cuba, the story picks up some traction. Oswald comes off as a totally unstable person. As one mob figure is quoted years later, Oswald didn't know if he was working for a pro-Castro or an anti-Castro organization. And the book definitely convinces in relation to that. For a while, I was thinking to myself, this is proving the nutty lone gunman theory. Then I realized, just because the guy is a nut, doesn't mean he wasn't being used by somebody. And when you read about Ruby's and a few other low-level mob figures' actions around the day of the assassination, and that Oswald had an uncle in Marcello's crime family, it becomes hard to doubt that the somebody was the mob.
The thesis of the book is that Oswald was the instrument of a somewhat improvised alliance - conspiracy may be too organized - between anti-Castro Cubans, right-wing Americans down south, a couple of strange Europeans, and the Mafia. The contours of this alliance are unclear. Certain Mafia figures are named, particularly Marcello and Trafficante, but also the 1975 murder victims, Giancana, Hoffa and Roselli. One mob figure is specifically identified as having carried messages between two of those names, relative to the intent to kill JFK, but it is long before Dallas and there is no tie to Ruby or Oswald in the message. There is no one as notorious from the other groups tied as closely to the murder, although there are a couple of low-level anti-Castro names in Dallas near the relevant time and a couple gun dealers/runners as well. The motives for the murder are mixed: was it designed to provoke a US invasion of Cuba? Or was it just elimination of the Kennedys from the executive branch, to turn down the heat on the mob? Maybe both. The author lays them all out there but has little hard evidence of the motives.
Anyway, although most of the relevant witnesses are dead, and probably not a lot of documentary evidence remains unexamined, and so the full details will never be fully proved, I thank the author for doing a terrific job, for history's sake, of compiling what evidence there is of the forces that were likely behind Oswald.