At the height of the cold war, the American government arrests a Soviet spy in New York City. The authorities and the justice system have already decided that the spy will be hanged. However, because America is a democracy, the spy nevertheless deserves to get his day in the court. But, the judge presiding in the case has already decided before even the case begins that he will sentence the spy to death. Also, no sane lawyer in the country wants to take the case because of appearing to fight for a spy. So, what does the government do? The government convinces (actually requests) James Donovan (played brilliantly by Tom Hanks), a financial lawyer to represent the Soviet spy in the courts because no "criminal lawyer" in the country wants to do that job. Donovan decides to take the case as a "patriotic" duty, to uphold the facade that even Soviet spies get their due process in American courts. However, not everything goes as planned. Posting any more details here would be a spoiler.