In this analysis of the 1963 assassinations of South Vietnamese leader Ngo Dinh Diem and President Kennedy, journalist O'Leary (Presidential Follies) and novelist Lee (The Stickmen, etc.) promise a lot more than they deliver. They claim that a French heroin syndicate, the U.S. Mafia and top South Vietnamese officials--the latter upset over alleged U.S. involvement in the killing of the Diems--conspired to kill Kennedy. The authors themselves admit in an epilogue that "every book written on the Kennedy assassination will be no more than a writer's hypothesis." Nor does their occasionally overblown language inspire confidence ("There are probably more people who believe that the world is flat than believe that JFK was shot by Lee Harvey Oswald alone"). Conspiracy theorists and JFK assassination buffs might find themselves compelled by the case made here; others will want to consider more sober accounts of what occurred in Dallas in November 1963.