Melvin Purvis of the FBI is famous for catching John Dillinger and “Pretty Boy” Floyd. Unfortunately, he made it into Hoover's bad graces and went from being his favourite protégé to being despised by the director. Hoover completely destroyed his career. He reportedly killed himself with the gun he was given as a gift for his service in the force. Hoover neither attended his funeral nor sent his condolences.
Amidst rumors of a conspiracy by the Axis powers to diminish America’s capacity to engage in hostilities, the FBI is called into action. Special Agent Chess Power is empowered by Deputy Director Melvin Purvis to put together a plan to thwart the efforts of a mysterious team known as the Triad. Power heads out to Alcatraz Island and enlists the aid of criminal genius Alvin Karpis in return for his parole.