Eric O'Neill, a low-level surveillance expert with the FBI, believes he is accomplishing his dream of becoming a full-fledged agent, with his unexpected promotion and assignment to clerk for Robert Hanssen, a renowned senior agent with 25 years in the FBI. However, he soon learns the reason for his promotion is to gain Hanssen's trust and find proof that he is a traitor to the country. Determined to draw the suspected double-agent out of deep cover, O'Neill finds himself in a lethal game of spy vs. spy, where nothing is as it seems.