In one of history’s most fascinating unsolved mysteries, former Teamsters president Jimmy Hoffa went missing on July 30, 1975, never to be found. Hoffa, a hero to many working Americans, played a major role in the growth and development of the trucking union. But he fell afoul of the law, with allegations that the powerful pension fund was under mob control and used, among other things, to finance Vegas casinos. What exactly happened to Hoffa that day, and why? Recently declassified FBI files and interviews with people close to the story allow a detailed accounting of what likely occurred. The investigation is an exploration of Hoffa’s final days and hours and a revelatory window on power and corruption in the post-war era labor movement.