This book sounds awesome, lifted the review from another site...
Not a book on the Kennedys per se, it's more of a historical crime novel centring around the Kennedy era with both Robert and John F as relatively minor characters, but I can't recommend American Tabloid by James Ellroy highly enough. It's fiction based around fact, so you get all the main players of the time: the mobsters, the teamsters, the FBI, the CIA, Cubans, KKK, Kennedys, you name it, but you also get a KILLER storyline. The way Ellroy writes is like full-immersion into the times with all the language and violence, fear, racism, bigotry and broads that entails.
It begins:
"America was never innocent. We popped our cherry on the boat over and
looked back with no regrets. You can't lose what you lacked at
conception. The real Trinity of Camelot was Look Good, Kick Ass, and
Get Laid. Jack Kennedy was the mythological front man for a
particularly juicy slice of our history. He called a slick line and
wore a world-class haircut. Jack got whacked at the optimum moment to
assure his sainthood. It's time to demythologise an era and build a
new myth from the gutter to the stars. It's time to embrace bad men and
the price they paid to secretly define their time. Here's to
them..."
American Tabloid covers 1958 - 1963, finishing at the exact moment that "Bad Back Jack" bought the farm in Dallas and the sequel, The Cold Six Thousand, picks up immediately where that left off and goes through until the deaths of RFK and Martin Luther King. Both are masterpieces. The third in the trilogy is planned to cover the years between RFK dying and the Nixon Administration/Watergate.
