Philip and Elizabeth discover that their murdered colleague Robert had a wife they never knew about. As they try to determine what she knows and where her allegiance lies, Stan's investigation into Robert's death puts him hot on their trail.
A mole hunt within the KGB causes suspicion amongst allies and shatters trust within the Jennings' marriage. Meanwhile, Stan's plan to keep his mole safe puts her at even greater risk of discovery.
Stan pursues a lead that puts him on the trail to one of Gregory's crew members, closing the gap between him and Elizabeth, and reigniting some of the deepest conflicts between her and Philip.