Based on the true story of FBI agent Eric O'Neill, this tense espionage thriller follows a young operative assigned to clerk for Robert Hanssen, a senior FBI agent secretly suspected of being the most damaging spy in American history. As O'Neill attempts to gain the brilliant, paranoid Hanssen's trust while gathering evidence of his treason, the psychological pressure threatens to destroy him. Chris Cooper delivers a chillingly plausible portrait of a man who betrayed his country for over two decades while maintaining a facade of devout patriotism.