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.

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

Danger mounts for Elizabeth and Philip as they get closer to the inner circle of the CIA Afghan Group.

Philip juggles the many women in his life while Elizabeth takes drastic measures to complete a mission. Stan asserts a plan to save Nina with an unlikely ally.

Philip and Elizabeth deploy a plan for the C.I.A.'s Mujahideen visitors.

Philip and Elizabeth's home and work lives collide in new and dangerous ways. Nina struggles to figure out her next steps. Arkady assigns Oleg and Tatiana to an operation with uncertain potential.

Martha hosts an unexpected guest; Philip and Elizabeth must work a formidable Mujahideen commander.

Elizabeth and Paige take a trip that lands them in treacherous territory.

Elizabeth and Phillip are supposed to get a biological weapon sample but fail to make the exchange when someone is watching. Nina works Anton in hopes it will lead to her freedom. Paige wonders if she can trust Pastor Tim with her secret.

Martha must finally face the truth she has denied - and her life may never be the same. Plus, a chilling new development in William's work forces the Jennings to face the realities of what a biological war would mean.

The Centre rushes to prepare Martha's exfil as Directorate S agents try to locate her but, it seems that a backup transport was also ordered. FBI tears up the Clark Westerfeld apartment. Martha almost walks into the FBI dragnet. Philip is overcome with self-recrimination...KGB may kill Martha. The FBI intercepts a call to Martha's parents from Woodley Park and stake out the area. Philip gets a call from Rock Creek Park; Elizabeth races to reach her and brings her in bruised but alive. Oleg does not know why backup transport was ordered. Gaad waxes philosophical about his FBI career in flames as the Jennings kids drink beer with Stan's son. Philip is finally honest with Martha, over Elizabeth's objections. Martha knows that she will be completely alone in Moscow. Will tomorrow's plane carry one rat or two? Or will Martha bite the Valium bullet and refuse to be forced to defect and commit further treason?

The Jennings hit their breaking points as they try to handle their local agents such as Martha.

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?

When Paige's long-ago indiscretion threatens to resurface and destroy the family, Philip and Elizabeth find themselves scrambling - and Paige finds herself reevaluating who her parents really are.

As Paige deals with last episode's trauma, she sees her mother in a new light... and finds she has inherited some of her parents' skills. Plus, has Oleg reached his breaking point with Stan?

In the season 4 finale, Elizabeth & Philip race against the FBI to retrieve a mysterious package. Paige finally begins considering whether or not she would like to enter the family business.

Paige's snooping leads Philip and Elizabeth to make a choice that could shift the balance of their lives forever. Stan and Aderholt's recruitment of Sofia suddenly bears fruit.

As the summit fast approaches, Elizabeth enlists Philip's help for a mission that could yield game-changing intel.

Elizabeth chooses a side in the internal soviet fight, meanwhile Stan's suspicions of Elizabeth and Philip get stronger.