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.

After Yurchenko's shocking disclosure, the CIA and FBI mobilize to bring the brilliant Edward Lee Howard to justice. Despite Howard being fingered as the mole, Sandy remains concerned about potential agency leaks and works tirelessly to prove that her asset, General Polyakov, is attempting to establish contact with the CIA. With the rest of the CIA distracted by bigger matters, Ames develops an unlikely bond with Yurchenko during a trip to Canada.