Perhaps the most repeated line from the spy novelist extraordinaire John le Carré’s 1974 book Tinker Tailor Soldier Spy is the assessment, made by one of his compromised Cold Warriors, that “the secret services are the only real expressions of a nation’s character.” Though it’s hard to beat as a sound bite, Le Carré actually amended the statement in an interview some decades later by replacing “a nation’s character” with “a nation’s subconscious.” He could’ve been anticipating FX’s hit espionage thriller The Americans. The show, which capped its fourth and, by far, most compelling season last night, understands that national-security concerns during the Cold War were determined to a large extent by the bogeymen that haunted nations in their sleep.

What sets the show (and this season, in particular) apart is that its version of cloak-and-dagger has always gone deep on questions of personal versus collective loyalty, something that Le Carré has also suggested defined operatives during the Cold War. The Americans may talk about strategic defense systems, Afghanistan, and biological weapons, but its juiciest bits are about intimacy. The show’s protagonists, spy couple Philip and Elizabeth Jennings, are played with remarkable depth and nuance by Matthew Rhys and Keri Russell; they’re attractive KGB agents in deepest cover, settled in Reagan-era Washington, DC, and passing themselves off as suburban American travel agents with a home and family. Some two decades earlier, the KGB arranged their identities, marriage, and, theoretically, Elizabeth’s subsequent pregnancies. (The show’s richest irony is that their school-age children, Paige and Henry, are, indeed, full-fledged Americans.) Elizabeth (real name: Nadezhda) is generally colder and doctrinaire, whereas Philip (real name: Mischa) is more likely to call audibles, which include purchasing a bitchin’ Camaro and pushing for a loving relationship with his spy wife after decades of watching each other don disguises, sexually seduce targets, and commit strings of remorseless murders. (In an odd twist on life imitating art, Rhys and Russell have now become a couple with a baby of their own; the show’s camerawork was tasked with hiding her pregnancy this season.)

Through the magic of television, Philip and Elizabeth end up living across the street from FBI counterintelligence agent Stan Beeman (Noah Emmerich). This would be completely implausible if Stan, who had a fleeting suspicion about the couple early on, weren’t failing so stirringly at living the dream that Philip and Elizabeth fake so well. One of the subplots that makes The Americans such a multilayered, if bleak, masterpiece concerns the disintegration of Beeman’s marriage, a road that finds him ping-ponging between lust for Nina Krilova (Annet Mahendru), a gorgeous Russian double agent he’s tasked with handling, and murderous, vengeful distress after the death of his FBI partner. Since all roads in the series lead back to the duplicitous, there’s a suggestion that a previous deep-cover assignment not unlike the Jennings’ helped turn Stan emotionally opaque.

What does it say that Philip and Elizabeth slowly lose their opacity (to viewers, at least), as they become more romantically involved with each other and attached to DC through their children? The season has fixated on the fallout from the couple’s reluctant decision to tell Paige (Holly Taylor) of their true origins. It’s one of two big reveals this season that could bring their world crashing down on them. “Our work makes the world safer,” they tell their daughter, in the most vague terms possible. Meanwhile, a vial of the planet’s most deadly biological agent is stored in the basement for safekeeping. Inquisitive, 15 years old, and a recently baptized Christian, Paige is skeptical, not least of which because she’s being mentored by Tim (Kelly AuCoin), a pastor whom she’s witnessed being arrested for antinuke activism. Philip and Elizabeth disagree on whether their children should enter the family business (something that had been suggested by the KGB), but when it’s discovered that Paige has disclosed their identity to the pastor, options are limited: It’s either get rid of her mentor or try to keep him close by carefully turning their daughter into an operative. Near season’s end, there’s a brilliant scene where the pastor and his wife are at the Jennings home for dinner when Agent Beeman, the hungry divorcé across the street, shows up. Paige can barely contain her astonishment as Philip tells the agent what any suburban Dad might: “Pull up a chair, stuff your face.” The tension at the dinner table is subdued but palpable.

Because the show is set in the ’80s (four seasons in, it’s now 1983), viewers are privy to an outcome that Philip and Elizabeth have no way of anticipating: The Wall will fall before the end of the decade. It’s safe to say that this isn’t the result the couple is working toward, even though The Americans doesn’t have a strict ideological stamp beyond its color palette—the flat, well-lit browns of Washington tend to go gray and dour when we reach Moscow. Still, by season’s end, Cold War fatigue is already beginning to show on all sides: Agent Beeman has grown tired of the tit-for-tat body count; Russian science officer Oleg Burov shares a pertinent piece of info with the FBI; Elizabeth is forced to contemplate how Henry, her happily oblivious child, might adjust to a new life elsewhere, perhaps even Russia. A lonely Russian operative rivetingly played by Dylan Baker even suggests withholding the biological agent from their KGB bosses. Le Carré’s words resonate here: “The Cold War was really a game of loyalty: what you owe to Caesar, what you owe to your country and what you owe to your own sense of personal ethics and morality.” Perhaps fittingly, in the finale’s penultimate scenes we witness Paige’s first makeout session while Philip and Elizabeth plot the family’s next move. Will Season 5 reawaken the old bogeymen?