Working with thousands of previously unreleased documents and drawing on more than one thousand interviews, with many witnesses speaking out for the first time, Joan Mellen revisits the investigation of New Orleans district attorney Jim Garrison, the only public official to have indicted, in 1969, a suspect in President John F. Kennedy's murder.

Garrison began by exposing the contradictions in the Warren Report, which concluded that Lee Harvey Oswald was an unstable pro-Castro Marxist who acted alone in killing Kennedy. A Farewell to Justice reveals that Oswald, no Marxist, was in fact working with both the FBI and the CIA, as well as with U.S. Customs, and that the attempts to sabotage Garrison's investigation reached the highest levels of the U.S. government. Garrison interviewed various individuals involved in the assassination, ranging from Clay Shaw and CIA contract employee David Ferrie to a Marine cohort of Oswald named Kerry Thornley, who at the very least was a Defense Intelligence Agency asset. Garrison's suspects included CIA-sponsored soldiers of fortune enlisted in assassination attempts against Fidel Castro, an anti-Castro Cuban asset, and a young runner for the conspirators, interviewed here for the first time by the author.

Building upon Garrison's effort, Mellen uncovers decisive new evidence and clearly establishes the intelligence agencies' roles in both a president's assassination and its cover-up, set in motion well before the actual events of November 22, 1963.