"The Americans," FX's Cold War drama about KGB spies posing as a married couple in Ronald Reagan's America, had the poor timing to arrive as a very good new show near the start of what turned out to be an incredible year. Had it debuted in a different period — even a year or two earlier — it would have set a very high bar to clear for all that followed and been a constant point of comparison. But there was just so much quality TV in 2013 that it kept slipping behind other work, even though it had so much to recommend it. When I did my best-of rankings for the year, I wound up putting it 18th, simultaneously kicking myself for doing so while struggling to argue that I preferred it to the previous 17.

We're still pretty early in 2014, and who can say what the year (which has already given us HBO's mesmerizing "True Detective") will have to offer, but it's hard to imagine "The Americans" (which returns tomorrow night at 10) getting lost in the shuffle this time around. It's taken a major creative leap — the kind that can elevate a show from a strong example of its era to one that transcends eras — and as I barreled through the five episodes FX sent out to critics, I felt my pulse quickening in that way I want to feel so often in my job but so rarely do: when something good becomes something great.

Again, "The Americans" had plenty going for it a year ago. The premise was gripping as both suspense fodder and an examination of relationships, asking the same basic question that KGB operative Philip Jennings (Matthew Rhys) kept asking of "wife" Elizabeth (Keri Russell): if you live with someone for decades, pretend to be married to them, and conceive and raise children together, at what point does it all cease to be an act? Rhys and Russell were superb, as was Noah Emmerich as their FBI agent neighbor Stan Beeman, at once oblivious to the danger across the street and a ruthless spy hunter. And the period touches were all spot-on, capturing the look and sound of the early '80s without turning into a cartoon recreation of them.

And it's not that the creative team, led by producers Joel Fields and Joe Weisberg, made drastic changes to the structure or style in between seasons. James Brolin doesn't join the cast as Reagan, who becomes best friends with the Jenningses after Elizabeth accidentally saves him from choking on a jellybean. We don't start getting flash-forwards to Philip in the mid-'90s, sporting a ratty ponytail and wispy mustache(*), philosophizing about the decisions he and his wife made back in the day.

(*) Though, oddly (especially since the episode was filmed months ago), one of his disguises makes him look uncannily like Matthew McConaughey in the 2012 "True Detective" scenes. 

What's happened is what you hope will happen when a show goes from its first season to its second: basic fine-tuning, emphasizing the things that worked well in year one, finding ways to either fix or eliminate what didn't.

The scenes with Jennings kids Paige (Holly Taylor) and Henry (Keidrich Sellati), for instance, tended to be a weak spot last season. But where other cable dramas (like a certain Showtime series that also deals with enemies of the state living undercover in America) only get deeper into trouble with their teenage characters as they go along, "The Americans" season 2 quickly finds multiple ways to emphasize how important Paige and Henry are, both to their parents and the series.

And boy howdy does season 2 play up the show's strengths. Like so many of the great 21st Century dramas, "The Americans" is a Trojan Horse show, telling intricate and thoughtful stories about marriage, hidden inside the exciting genre trappings of a spy thriller. Philip and Elizabeth have weekly missions where they beat, kidnap, threaten and occasionally kill their enemies, but they're also constantly dealing with the compromises any couple has to make, questions of trust and faith and trying to keep their kids safe in a world that would be growing ever-scarier even if they really were the travel agents they claim to be. And just as Tony Soprano being a mobster raised the stakes of his disputes with his mother and his uncle, so does the danger of a double life in the KGB heighten every bump in the Jennings marriage.

In one episode, we see them in the laundry room divvying up their chores for the week — they just happen to include infidelity, blackmail, kidnapping and Philip's outside marriage (the only semi-legal one he has) under an assumed identity to an administrative assistant in Stan's office. As the season moves along, one of the kids develops an interest in organized religion; when "The Good Wife" tells that exact same story, it's a drag, but when the parents are godless Communists like Philip and Elizabeth, it becomes another fundamental threat to their way of life.

Season 1 toggled back and forth between Philip and Elizabeth trying to treat their pretend marriage as the real thing, ending with the both of them agreeing to do so. Season 2 finds ways to introduce even greater tension, even as they're a more fundamentally sound unit, while also adding a whodunnit element that spices things up nicely. 

One of the discoveries of the first season was Annet Mahendru as Nina, a Soviet embassy worker whom Stan Beeman blackmailed into feeding him information, before she went back to her superiors and turned triple agent. She's even more prominent this year, so marvelously hard to read even as she sleeps with Stan, then files explicit reports about it to the KGB, and she in turn gives Emmerich so much to play as the noble but weak Stan. And though Margo Martindale, who brought so much nuanced menace to her role as Philip and Elizabeth's handler Claudia in season 1,  is now full-time on CBS' "The Millers," she gets to return now and then and instantly makes everyone around her better.

The show's soundtrack continues to feature the perfect kinds of songs, which weren't overplayed back in the day (or on classic rock radio or period movie soundtracks in the years since), but that instantly evoke both the period and the emotions of the scene. Episode-ending music montages have become an overused cliché in cable drama, but there's one at the close of this season's third episode that's a perfect marriage of music and pictures, bringing the hour's story and character arcs to a close in a more beautiful way than a few dialogue scenes could have.

The new season plays very much like Fields, Weisberg, Graham Yost and the rest of the production team did as thorough a soup-to-nuts assessment of their strengths and weaknesses and how to fix them as one could imagine. Even a relatively minor flaw (if you can call it that) like the show's fans fixating on Philip and Elizabeth's wig disguises, to the point where undercover scenes became funny when they weren't meant to be, is solved with one swift, brutally elegant move in the season premiere. Without spoiling it, I'll just say that the minute it happened, I forever stopped questioning why those things never come off.

As viewers watching these stories from the relative safety of 2014, we know that Mr. and Mrs. Jennings will wind up on the losing side of history. The future of "The Americans," and what its legacy might be whenever it finishes what had better be a long run, has yet to be written.

Its present, though? Absolutely dynamite.

Alan Sepinwall may be reached at sepinwall@hitfix.com