As the Cold War enters its final act, the CIA is sent scrambling when a rendezvous with a prized asset goes horribly awry. CIA officer Sandy Grimes begins her investigation into the source of the problem and quickly discovers that this lost asset is just the tip of the iceberg. Little does she know that this is just the beginning of a decade-long mole hunt, and the mole is one of her cohorts - Aldrich Ames.

The CIA scores a major break when Vitaly Yurchenko, a high-ranking KGB officer, defects to the US. Assigned as the lead in the debriefing, Aldrich Ames engages in a verbal cat-and-mouse game to determine whether he is in danger of being ratted out. Ames considers taking drastic measures when Yurchenko reveals that he knows of a mole in the CIA. Meanwhile, Sandy frets over the safety of a beloved and esteemed asset, General Dmitri Polyakov.