Eric O’Neill (Ryan Phillippe) is a young FBI employee assigned to work undercover as a clerk to Robert Hanssen (Chris Cooper), a senior agent he is told is suspected of being a sexual deviant. Hanssen has been recalled from a detail post at the State Department to FBI headquarters ostensibly to head up a new division specializing in Information Assurance. Initially, Hanssen insists on a strict formality between the two men.