When Karl Marx wrote that history repeats itself, first as tragedy, then as farce, he couldn’t have known that a television show would find a way to take those two versions of history and combine them. But over the course of three seasons—the fourth premières this week, on FX—“The Americans” has become one of the most multilayered dramas on TV; nothing else can match its combination of genuine sadness and muted, mordant hilarity. Watching it, you feel both dread and delight—a bitter kind of happiness. It’s the whiskey sour of television shows.

Essentially, “The Americans” is a show about espionage: it follows Nadezhda (Keri Russell) and Mischa (Matthew Rhys), two sexy Soviet spies who pose as a married couple named Philip and Elizabeth Jennings. Their partnership was arranged years ago by the K.G.B., but, in the intervening decades, their sham marriage has become real, and they now have two children, Paige (Holly Taylor) and Henry (Keidrich Sellati). They run a travel agency and live in a suburban house outside Washington, D.C. In the basement, they plan seductions, kidnappings, and assassinations. They are efficient killers, and one mark of that efficiency is the ease with which they return to family life when the work is done—strolling into the kitchen, leaning in for a kiss on the cheek.

The title of the show has many meanings. It refers to Paige and Henry: unlike their parents, they are “real” Americans, hooked on Christianity and video games, respectively. But it also refers to Philip and Elizabeth, who are, to varying degrees, at home in what’s supposed to be enemy territory. And it refers to us, too. The implication is that we are all, in some sense, undercover in our own lives. Parents who aren’t spies nevertheless hide things from their children and each other; even people with nothing to hide (if such people exist) must find ways to perform their normality. The show’s theory is that every John and Kate has an inner Mischa or Nadezhda; we all speak Russian, or some other, private language, in our sleep.

By means of this parallel, the show has become an empathetic, sophisticated family drama in addition to a spy thriller. Philip and Elizabeth are as overworked as any American couple (with the travel agency and their work for the K.G.B.’s “Moscow Centre,” they each have two jobs). As parents, they struggle to shield their children from the adult world while also shepherding them into it (last season, they revealed their true identities to their teen-age daughter—for her, it was a shocking introduction to Real Adult Life). As married people do, they cross and recross the borders dividing privacy from intimacy, independence from codependency, lust from boredom. My colleague Emily Nussbaum has written that the series is “about life as kinky role play”: Philip and Elizabeth are always dressing up in costumes and sleeping with other people, and those experiences follow them home. Theirs, in short, is a typical family, but with its weirdness magnified. In the show’s heightened world, the ordinary injuries of family life become more heartbreaking. The attempts that middle-aged people make at rejuvenation—new hairstyles, innocent flirtations—expand into sinister, horrific crimes.

The dirty secret of “The Americans” is that it’s funny. In nearly every scene, there’s an item of clothing or a turn of phrase to make you smile and remember the nineteen-eighties. The show’s setup is intrinsically humorous—in part because it’s loosely based on a real (and spectacularly unsuccessful) Russian spy program that was busted up by the F.B.I. a few years ago. And “The Americans” is also a romantic show. You root for Philip and Elizabeth, sighing when signs of affection appear on their watchful, well-regulated faces. As it happens, at some point during the first few seasons, Russell and Rhys became a real-life couple; they’re now expecting a child. In a piece about their romance, People magazine pointed out that the actors seem to have shared an experience with their K.G.B. counterparts: “What started as a relationship all for show evolved into authentic affection and, soon, a parenting partnership.” There is, in short, a sweetness to the series. It’s never unsullied; nothing the Jenningses do is ever pure. But it’s there.

That sweetness is more effective, of course, because the show is so sour. “The Americans” is brutally violent, and its violence is often unleashed suddenly, for maximum horror. And the series refuses to offer its characters ways out of their predicaments. There is no hope for the Jenningses, or for anyone in their extended social circle. Their closest family friend is Stan Beeman (Noah Emmerich), an agent in the F.B.I.’s counterintelligence division; it seems likely that, someday, Philip and Elizabeth will have to kill him. (The same goes for Paige’s pastor, to whom, at the end of last season, she entrusted the secret of her parents’ identities.) The characters have no choice but to keep on lying and murdering; and so, instead of dwelling on the blood-soaked past and future, they try, as best they can, to live in the moment: “Everybody lies, Paige—it’s a part of life,” Elizabeth said, last season. “But we’re telling the truth now. That’s what’s important.” That kind of presentism is a delicate lifeline.

Occasionally, in flashbacks, we get glimpses of Mischa and Nadezhda’s childhoods: the Soviet state was in loco parentis, and the K.G.B. was abusive. (Nadezhda was raped by an instructor; Mischa’s training was brutal in other ways.) Now that the Jenningses have children of their own, the K.G.B. has come to occupy the grandparent role: Philip and Elizabeth’s handlers, Claudia (Margo Martindale) and Gabriel (Frank Langhella), are older and evasively grandaprent-ish. Through the lens of espionage, the series is showing us how abuse can be handed down from one generation to the next: Philip and Elizabeth are good parents who care about their children, but their baseline—their idea of what’s normal—is totally off the mark. From this perspective, there’s something psychotherapeutic about the show’s nineteen-eighties setting. For a certain generation of viewers, “Mad Men,” which was set during the sixties, provided a window into the parental psyche. Perhaps “The Americans” performs the same function for a younger generation, in a lurid, dreamlike way.

But the darkness in “The Americans” spreads out beyond family life. It’s geopolitical and historical. On some level, the show is about terrorism: a drama about the family life of Syed Farook and Tashfeen Malik would be unwatchable, but we’re far enough away from the Cold War for a show about a Communist sleeper cell to be appealing. (Philip and Elizabeth aren’t, strictly speaking, terrorists, but there’s no question that they’ve been “radicalized”; the first few episodes of the new season, meanwhile, deal with a plot to steal biological weapons.) And, more generally, the show is about the cruelty of history. No one on the show realizes it, but the Cold War is coming to an end. Everything Philip and Elizabeth do is, ultimately, for naught; worse than that, it’s unnecessary. And yet their determination, their dedication, is undimmed, as is their willingness to sacrifice not just themselves but their family for the Soviet cause.

“No matter what they write now, there was such a thing as a Soviet person, with a Soviet character,” one man tells Svetlana Alexeivich in “Voices from Chernobyl,” her oral history of the nuclear disaster. A schoolteacher from a nearby town whose students volunteered for the cleanup tells Alexeivich about the feeling of working in the irradiated zone: