President Kennedy was assassinated 42 years ago this month, and still the debate rages as to who killed him and why. Now, a new book, Ultimate Sacrifice: John and Robert Kennedy, the Plan for a Coup in Cuba, and the Murder of JFK, claims to provide "the missing piece… the truth behind the events surrounding" the assassination.

Written by long-time assassination researcher Lamar Waldron, with the help of author and Air America radio host Thom Hartmann, the book is being published by Carroll & Graf with an unusual degree of secrecy: the national accounts were pitched the book in New York by Avalon CEO Charlie Winton last spring only after they signed nondisclosure agreements. Still, a first printing of 57,000 is just off press and will be in stores by November 18. Does the country remain intrigued by the mystery of what happened at Dealey Plaza? Carroll & Graf publisher Will Balliett thinks so. "Books on this topic have a passionate niche, but this doesn't feel like a conspiracy book, it feels like history."

The "missing piece" promised by the book is evidence that the Kennedys planned a "palace coup" in Cuba, set for December 1, 1963, to be followed by a full-scale invasion; furthermore, that the coup was infiltrated by the Mafia, which saw an opportunity to kill the president whose brother was vigorously pursuing them. "Our investigation has produced clear evidence that the crime bosses arranged the assassination so that any thorough investigation would expose the Kennedys' plan," write the authors. Waldron says that the coup plan "is corroborated by many recently declassified military and CIA documents quoted for the first time anywhere." The book also details a previously unknown assassination attempt on Kennedy in the days before Dallas. According to the book, this attempt had more than a dozen parallels to Dallas—complete with an Oswald-like patsy—and was kept out of the press at the time by the Kennedys in order to protect the plan.

The popular view that Kennedy, during the Cuban Missile Crisis of October 1962, had engineered a great feat of political brinksmanship and avoided nuclear war assumes that he promised the Soviet Union that the U.S. would not invade the island nation 90 miles south of Miami. However, this notion has slowly lost credibility as documents have become declassified. Former Secretary of State Dean Rusk, as long ago as 1990, told the authors that such a promise was contingent on Castro agreeing to on-site weapons inspections by the U.N. Presidential historian Michael Beschloss endorses that view and is quoted in the book as saying that Kennedy "deliberately avoided" making any unconditional pledge not to invade. And as we have seen most recently in Iraq, noncompliance can serve as pretext for an invasion.

Among the evidence unearthed by Waldron are "hundreds of CIA, military and State Department documents" specifically referring to a plan for a coup in Cuba, conceived by Robert Kennedy, drafted by the military with support from the CIA. There is also a previously undisclosed cable, from CIA director John McCone to the CIA station in Miami, stating that a "general uprising [is] scheduled for 1 December." The "palace coup" was intended to look like a homegrown changing of the guard. The plan called for post-coup elections, Cuba's severing of ties with the Soviet Union and a partnership with the United States.

The authors argue that three Mafia kingpins—Carlos Marcello, Santo Trafficante and Johnny Roselli—learned of the plan and "realized that the government would go to audacious lengths in order to avoid revealing it to the public."

Waldron said that it was the story that RFK aide and Bay of Pigs veteran Enrique "Harry" Ruiz Williams told him back in 1992 that provided the blueprint for his research through the declassified material. "What we found basically corroborated the story that Harry, along with other Kennedy associates, told us." The authors interviewed various Kennedy insiders who confirm either the existence of the coup plan or the role of the mob, including Rusk, the late Dave Powers, Richard Goodwin and Pierre Salinger.

Over the years, the publishing industry has embraced the JFK question. More than 80 books are still available on all aspects of the assassination, and no less a literary giant than Don DeLillo has weighed in with a major work of fiction. With a debate so lively, why the secrecy surrounding the publication of Ultimate Sacrifice? Avalon's Charlie Winton (Avalon owns Carroll & Graf) admits that the secrecy is partly due to his attempt to break the story with various media partners, which effort is still in the works. He also points to the role that books can play in shaping public opinion, and he didn't want this book to be suffering rebuttals before the evidence was out there in full. "My job is to orchestrate the publishing process so that the news and the book arrive in the marketplace at the same time," says Winton.

Winton is a veteran of JFK publishing, having built a "rep" (his word) for his involvement in at least a dozen Kennedy books, including Jim Marrs's Crossfire, upon which much of Oliver Stone's JFK film was based, and books by former government investigators Gaeton Fonzi and William Turner. Winton's also no stranger to books about pretexts for invasions. Eighteen months ago, Carroll & Graf published The Politics of Truth by Joseph Wilson. Wilson pointed his finger at Lewis Libby and Karl Rove as sources of the leaks about Wilson's wife's CIA identity, charges now partially corroborated by a special prosecutor's indictment of Libby.

"I didn't buy Lamar's book until three years ago," says Winton. Because key sources were still alive and so much was still classified, an earlier version was shopped as a historical novel, but Winton wanted a book with definitive documentation. "Fortunately," he says, "in the wake of the Oliver Stone film, Congress moved to declassify many of the top-secret documents that pertain to the assassination and to the roles of the CIA and the State Department at that time." Winton says that Waldron has combed through the flood of released material and basically confirmed "what Harry Williams told him 13 years ago"—the Mafia did it, knowing that their knowledge about a coup in Cuba could ensure the silence of the government.

"Ever since Gerald Posner's Case Closed, I've wanted to do this," says Winton. "Because of my understanding of the subject, I knew that this book would provide the critical missing piece of the puzzle and, at least for now, be the definitive work."

One dispiriting element of this book's thesis is that the "ultimate sacrifice" of the title is the one made by the president himself. "He literally risked his life for the coup plan," says Waldron. "Despite being aware of the threat of assassination, he decided to go ahead as scheduled because the motorcade itself was part of the plan—it was designed to signal strength and resolve for the upcoming coup."