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.

As Philip investigates the fallout from the last operation, Elizabeth sticks close to home, concerned for her family until she gets a mysterious distress signal. Meanwhile, a walk-in arrives at the Rezidentura - providing both Nina and Stan with unique opportunities.

No one is safe as Philip and Elizabeth evacuate their children while trying to complete the mission. Stan holds Nina's future in his hands.

Tensions simmer between Philip and Elizabeth as they disagree over handling orders from the Centre. When Elizabeth loses key intel, Philip enlists Annelise on a mission with an unexpected outcome. Stan tries a new approach to mending his marriage with Sandra amidst learning tough news about Nina.

Elizabeth and Philip come together to deal with a mission gone wrong but struggle to reconcile their increasingly opposing ideologies. Stan welcomes a Soviet defector, Zinaida, to America. Nina acclimates to her new living arrangements.

Elizabeth and Paige take a trip that lands them in treacherous territory. After an emotionally charged mission, Philip turns to an unlikely source for solace. Stan’s plan to save Nina culminates in unforeseen ways.

The Day After premieres, making the stakes - and terrible consequences - of the Cold War plain. Even with that in mind, will Elizabeth be able to complete the painful process of the "Patty" operation?