As if their lives aren't dangerous enough, Soviet spies Philip (Matthew Rhys) and Elizabeth Jennings (Keri Russell) must deal with an extremely potent bioweapon on "Glanders," the Season 4 premiere of "The Americans" on FX.
Glanders, an infectious disease typically spread from horses to humans, has been weaponized by William (Dylan Baker), a turncoat scientist in Washington, D.C.
"I'm very sorry," KGB handler Gabriel (Frank Langella) apologizes to Philip and Elizabeth before vaccinating them against meningitis. "I tried to keep you out of it."
Coming into contact with glanders could prove fatal. And coming into contact with William, who's under FBI surveillance, could get Philip and Elizabeth imprisoned for life. That's why they turn back two times before intercepting William on his evening stroll.
While handing over a small vial encased in a box, William dismisses any hope that the spies are protected by their vaccine.
"This is to meningitis what bubonic plague is to a runny nose," William sneers.
When they arrive home, Philip and Elizabeth are approached by their FBI neighbor Stan Beeman (Noah Emmerich). He supposedly wants a private "boy talk" with Philip, who slips the vial into his coat.
Instead of a friendly chat, however, Philip is accused of being "very intimate" with Stan's estranged spouse, Sandra (Susan Misner).
"Are you screwing my wife?" Stan yells at Philip, shoving him against a wall.
Philip vehemently denies having an affair. But his biggest worry is that Stan cracked that fragile vial. Fortunately for Philip, the bioweapon remains intact.
Philip also has a tense exchange with his second wife, FBI secretary Martha Hanson (Alison Wright).
In Season 3, Martha planted a KGB listening device in the office of counterintelligence supervisor Frank Gaad (Richard Thomas). After the bug was discovered, Philip shielded Martha by framing computer specialist Gene Craft (Luke Robertson).
Now Philip breaks the news that he murdered Gene and made it appear like a suicide.
"What have you done?" Martha sobs. "What have I done? It's my fault. I killed him!" Martha eventually calms down and thanks her husband for being honest.
"I have to know everything," she says, "even if it's hard."
When Martha returns to work and nervously copies surveillance reports, she's startled by Stan.
"I know you liked Gene a lot," Stan says.
"I guess you never really know a person," Martha replies, "do you?"
Back at the Jennings household, daughter Paige (Holly Taylor) struggles with the revelation that her parents are spies.
Elizabeth sugarcoats her KGB missions, claiming she wants to "make the world a safer place for everyone." Paige is fearful and confused, however, and confides in Pastor Tim (Kelly AuCoin).
"If people are getting hurt, we have a responsibility," suggests Tim, who naively asks if Paige's parents would like to speak confidentially about their Cold War activities. Not a good idea, unless Tim wants to dramatically shorten his lifespan.
"We can't tell anybody else," Paige exclaims. "Ever!"
Finally, former KGB agent Nina Sergeevna Krilova (Annet Mahendru) grows closer to Jewish scientist Anton Baklanov (Michael Aronov), who was repatriated to Russia and forced to develop stealth technology. His future depends on test results for a prototype aircraft wing.
"If it fails," Anton laments to Nina, "they're done with me. I'll disappear into a camp."
To Anton's relief, the wing is nearly invisible to radar. This means Anton and Nina will continue working together. And this means Nina suddenly has leverage.
When Soviet official Vasili Nikolaevich (Peter Von Berg) tells Nina he won't consider a request, she counters that "it's a demand."