After the assassination of President John F. Kennedy, New Orleans District Attorney Jim Garrison becomes suspicious of the official story presented by the FBI and the Warren Commission. His skepticism grows when he notices inconsistencies in the case and the quick silencing of potential witnesses. Determined to uncover the truth, Garrison takes it upon himself to conduct an independent investigation. He and his team delve into the labyrinth of evidence, encountering a myriad of complex clues and contradicting testimonies that suggest a high-level conspiracy.

As Garrison digs deeper, he uncovers a trail that leads to a diverse array of individuals including clandestine government agents, anti-Castro Cuban exiles, and organized crime figures. The quest for the truth becomes an obsession for Garrison, as he faces criticism and even hostility from those who believe he's becoming paranoid or simply trying to exploit the national tragedy for his gain. His relentless pursuit not only strains his professional life but also puts his family's safety at risk. Undeterred, Garrison persists in his investigation, driven by the profound belief that the American public has the right to know the reality behind one of the most pivotal events in the country's history.