Martha is upset when Philip relates Gene's role in protecting her. The trip to Germany has repercussions for the Jennings family. Gabriel tells Elizabeth and Philip about William, who has samples of US biological weaponry, which they are to acquire. Back in USSR, Nina continues to leech onto Anton for her own freedom... or does she have another agenda? Pastor Tom continues to pry information out of a guilty and confused Paige, but they do not know the phone is bugged. Philip and Elizabeth have numerous problems meeting William without a tail. Either his new openness with Martha or his talent for killing are causing Philip to have very bad dreams about his childhood. Arkady is upset when he learns Tatiana is from the secret Dept. 12. Elizabeth and Philip make the acquaintance of burkholderia mallei. A distraught Stan accuses Philip of sleeping with Sandra, as he was not honest with Stan about continuing EST and Elizabeth does not even know. Written by LA-Lawyer

Philip quickly tries to hand off the small tin containing the biological weapon to an old Czech pilot; it turns into a public murder with the nervous pilot refusing the tin. The Centre wants access to the 4th floor of Ft. Dietrick. Gabriel tells Elizabeth her mother is dead; Elizabeth has an odd reaction. To explain Stan's anger, Philip tells Elizabeth about EST and surprisingly, she asks if he would like her to go. Gaad gives Stan his opinion before he meets Arkady to share the bad news about Nina. After seeing her husband, Nina tries to help Anton contact his son in America and Nina is betrayed. Elizabeth listens to the bug she placed on the house phone to learn Paige told Pastor Tim their secret, but Paige confesses it to her mother, herself. Elizabeth and Philip agree Pastor Tim must die. Written by LA-Lawyer

Paige tries talking to Pastor Tim about him breaking her confidence with Alice but it does not go as hoped. Gabriel suggests taking Paige and Henry to the brand-new Epcot Center. Back in the USSR, Nina may experience what KGB, GRU and/or the 2d Directorate considers exceptional punishment. Gabriel meets with Claudia; later, he is found near death with Glanders by Philip and Elizabeth. They force the double agent scientist to help save their handler. Stan is suspicious of Martha. Things may be about to hit the fan in all directions but the four spies are out of commission, in quarantine for 36 hours. It may not be such a small world, after all. Written by LA-Lawyer

Elizabeth tries to cancel delivery of the package this weekend and scientist, William clips the steel cord, removing the pay phone receiver after the conversation. FBI Dennis pressures Martha to spend time together. At dinner, Martha tells him she is seeing a married man; meanwhile, Stan ransacks her home and flips through her edition of Kama Sutra. Elizabeth is having symptoms: either as a side effect of the Glanders antibiotic, or she is sick; and she has vivid fever dreams. Nina is still alive, but in solitary. Home in Russia (from his tour in the US) after his brother's death in Afghanistan, KGB Officer Oleg asks his father to help Nina, but his father demands a huge sacrifice in return. As Elizabeth and Gabriel lay sleeping, William confides in Philip. A number of surprising Russian decisions are made on two sides of the ocean but the results of one of them are chillingly final. Written by LA-Lawyer

Martha starts taking Valium. Philip gives her a contact phone number, which she must memorize and call only from a pay phone; her news about the Xerox copies alarms Gabriel and the Jennings. Oleg blames his father for brother, Yevgeny and Nina. His father, embittered about what the USSR has become, tells Oleg to go back to the US. Paige keeps asking for information; her parents tell her they are speaking to Pastor Tim and Alice. Oleg returns to the Rezidentura and tells Arkady and Stan about Nina. Hal thinks Martha is being followed; Philip clears evidence from the apartment. Philip delays Martha to Tuesday and Martha pops Valium. Paige makes a surprising discovery. Philip and Stan finally reconcile; Philip meets his ride, FBI Dennis, when he leaves the Beeman house. Philip and Elizabeth recognize his car. Written by LA-Lawyer

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? Written by LA-Lawyer

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.

Elizabeth completes the last steps of a very personal operation... but at what cost?

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 and 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.