Six things the book reveals
1 To protect their reputations, the CIA and the FBI attempted to hide the full story about Oswald's important trip to Mexico in September 1963 (less than a month before he shot Kennedy) where he told agents at the Cuban embassy he intended to kill the president. A top-secret memo in mid-1964 from Edgar Hoover about this never reached the Warren Commission.
2 The FBI hid other vital evidence about Oswald, including destroying, on the day he was killed, a threatening note he hand-delivered to the Dallas office in early November.
3 The navy pathologist destroyed his original autopsy report on the president as it was stained with Kennedy's blood. The autopsy photos and X-rays were kept secret from everyone by Earl Warren.
4 Warren, convinced from the beginning that Oswald had acted alone, cut corners that later helped nurture conspiracy theories. The commission suppressed information about Oswald's possible impotence and sexual orientation. Commission member, later president, Gerald Ford thought Marina Oswald's jeering of his sexual inadequacy may have driven Oswald to act.
5 Fidel Castro (pictured) met secretly with a Warren Commission investigator in a boat off Cuba to deny any involvement in the assassination.
6 Hoover's successor, Clarence Kelley, considered JFK's death could have been prevented, perhaps easily, had the FBI acted to pick up Oswald based on the information in its own files, particularly about the Mexico City trip.