On November 22, 1963, president John F. Kennedy is assassinated in Dallas. Lee Harvey Oswald is arrested for the crime and subsequently shot by Jack Ruby, supposedly avenging the president's death. An investigation concludes that Lee Harvey Oswald and Jack Ruby acted alone in their respective crimes, but Louisiana district attorney Jim Garrison is skeptical. Assembling a trusted group of people, Garrison conducts his own investigation, bringing about backlash from powerful government and political figures.