Do not read on unless you’ve seen “Chloramphenicol,” the fourth episode of the fourth season of “The Americans.”

At the end of Wednesday’s “The Americans,” the story of Soviet operative Nina Krilova (Annet Mahendru) came to a shocking end. Sentenced to death in a grim Russian prison, she was shot in the back of the head seconds after her sentence was read out. Wrapped in a burlap cloth, Nina exited the show, the victim of a series of political games that were rigged against her from the start.

In an interview with Variety, executive producers and showrunners Joe Weisberg and Joel Fields talked about why Nina’s poignant death played out the way it did. Both are spoiler-phobes, and with good reason — Nina’s death was an effectively gut-wrenching shock because it surprised both her and the audience. But Weisberg and Fields talked in depth about the thinking behind Nina’s death, and they offered a few hints about what her demise means for other characters. They also addressed how much longer the award-winning FX drama will run (the short answer: Philip and Elizabeth Jennings will be playing spy games for one or two more seasons at most).

So your show killed off Nina Krilova. Why are you history’s greatest monsters?

Joe: We’re hearing that a lot. You know, it had to happen. She had done so many terrible things, and the Soviets were getting fed up with her. They could only give her so many chances.

Joel: And we didn’t do anything.

The Supreme Soviet did it.

Joel: Yes, and very officially, too we might add.

Joe: Yeah. They followed the letter of the law. We based that on how they actually executed traitors back then, all of which came out after the fall of the Soviet Union. We followed both the legal code and also exactly how the execution squads carried out their work. The people being killed didn’t know it was going to happen. [The executioners] felt that was more humane if it was a real surprise.

In a way, it’s not respectful to give a character like that a happy ending, because that’s not truthful to how things worked out for many, many people under that system.

Joe: We agree with that. We try to focus less on the question of “Has the character run out of stories we have to tell? Has the character run out of real estate?” It’s impossible not to think that way to some degree, but we try to ask ourselves the real-world questions [i.e., what actually happened to prisoners in the Soviet Union].

Just speaking hypothetically, before she tried to pass that note via her husband, was there a chance for her to get out of that jam?

Joel: Yeah. She was on her way of getting out of the jam. A big part of the story we wanted to tell, and it’s a story that Joe and I have been plotting out over the course of the series, was that she’s changed. This is a person who is finally realizing that the process of sacrificing others for herself, putting her own survival first, had gotten her to a certain place, but it wasn’t the way she wanted to live anymore. She was opening herself up to being a different kind of person. She gets the transformation that comes with that, and she unfortunately pays the price that comes with that, given her circumstances.

It was really moving, in part because a meaningful character death does have that thematic resonance relating to what the show is about. So much of your show is about that dilemma — should you do the “right” thing, whatever that may be, or should you survive? Whether or not they think there will be a good outcome for them, sometimes these characters have to do something just to save their souls.

Joel: Yes. Absolutely.

To me, it seemed that her calculations had finally arrived at a place of, “I just can’t do this anymore and I’ll take the consequences.” Is that where you think she was right before that happened?

Joel: I don’t think she was expecting it to go this way.

Joe: I don’t know if she was even doing calculations. I think part of her transformation was becoming a person who was going to inhabit a different plane. She was through being Machiavellian and through making choices that were all about what was best for her. She was making fewer calculations and just following her heart and seeing where that led. Of course, you could say it led somewhere tragic, that’s obvious, but it also led her to a very beautiful place for that very short final part of her life. I think it led her to be alive in a way she had never been.

Can you talk a little about the dream sequence that we saw right before her death? Was it there partly to offset what happened moments later? Was it a fantasy along the lines of, “in a different world, it could have been like this”?

Joel: The idea of a series of dreams came to us very early in the process. We knew we wanted to explore her subconscious through a series of dreams, and we wrote them and rewrote them and conceived them and re-conceived them many, many times. Conceptually, [that part of the episode] has been with us a long time and practically, it went through many iterations. I’m not sure exactly how we landed at this one.

Joe: There’s something about the fact that she was in prison. She was going to be in prison for a while, so there were a limited number of things she could do. For her final stage, she was going to be in her cell, so we were going to be inside her head. That kind of sequence made a lot of sense, in terms of exploring what was in her head and what was in her heart.

I thought the director, Stefan Schwartz, did a great job of evoking the poignancy of the moment. Part of what made her death heartbreaking was that the place where it happened was so bland and average — the linoleum floors and the greenish overhead lights and the banality of it all made it that much more powerful. Was that something that you had always envisioned for the sequence? Did you and Stefan collaborate on that?

Joe: It was a real collaboration. We were able to give him this source material that described in great detail how the executions were carried out by these teams who planned everything. They were experts at making sure that they didn’t get blood on themselves and things like that. Stefan was able to design it and come up with the look of that stunning visual sequence, including that final dreamscape that you’re talking about, which was so moving and is a piece of the execution — but as its opposite. He put that together so beautifully that it’s hard to get those images out of your head.

Joel: He did a brilliant job, and to me, the last 10 minutes of this episode are just a triumph of this incredible team we’ve got — Diane Lederman, our production designer; [executive producer] Chris Long, our new producing director; Alex Nepomniaschy, our cinematographer this season, who just did brilliant work. Then there’s the special effects team that created that dream sequence.

Our technical consultant, Sergei Kostin, brought us the original research and gave us so many details, down to the fact that they would take the body away in a piece of burlap cloth. There are even little subtle clues — as Nina walks in, she passes a mop in a bucket by the floor.

Joe: One of the details that we got from our consultants is that these teams always had a person standing on each side of the person about to be executed. When they heard that their appeal had been denied and their execution would be carried out “shortly” — and that’s what they would say — the person’s knees would always buckle. They needed a person on each side to catch them and hold them up so that they could be shot in the next moment.

These details really help create an atmosphere and a mood. One that I thought about was that she put her shoes on before she goes to that dingy room. She’s trying to be a human being, she’s trying to have dignity, even in this horrible moment.

Joe: Well, the remarkable thing is they’re all trying to be human. I think part of it is that the executioners are trying to be human, too.

I watched the sequence a couple of times and the look on the face of the man who is reading the death sentence is not one of cruelty or disdain.

Joe: Exactly. That was so important.

Did you ever picture Nina having this level of importance in season four, back when you were first conceiving of the show?

Joe: I don’t think it’s a surprise, no. I don’t think we knew where it was going. A lot of people in season one were saying, about both her and Martha, “They’re going to be killed next episode, they’re going to be killed next episode.” And we knew that wasn’t true. We knew that each of them had a long arc coming, but I think with both of them, we didn’t know exactly how long and exactly where it was going. So if you had said then that they’d both be going into season four, I don’t think we would’ve been shocked.

Joel: The truth is, when we were working on it in season one, we knew it would be a long arc, but we didn’t know the details. By the time we got to the beginning of season two, we had spent a lot of time breaking story, and I think we really had all the pieces in place that you’ve seen play out. Had you asked us [in season one], we could have convincingly walked you through her story, certain it was going to end by the end of season three or the middle of season two. What we didn’t anticipate is that it would take so long to play it all out.

Speaking of Martha, she obviously knows more this season and thus is more intimately tied to the narrative. Will she continue to be a big part of the show because she offers kind of a counterpoint to the Jennings marriage?

Joe: I think we’re going to “no comment” on that one. We’re “no commenting” you. [laughs]

In any event, I would assume Nina’s death will have a big impact on Oleg.

Joe: You’ll see it more as you go along [this season] — people often thought that Nina is being isolated by herself in the Soviet Union, and we didn’t entirely see it that way. A lot of the stories you’ll see going forward tie into each other, probably better than they have in previous seasons. What this will do to Oleg and Stan is, as you say, going to be very important going forward.

Is it accurate to say that Stan finds out and that will have an impact on his story?

Joe: You could say that.

Joel: That this news will travel somehow seems inevitable on our show.

Maybe the mail robot spills the beans. Talking of Oleg, he wanted his father to help with Nina, and obviously that didn’t work out. Will he be coming back to the U.S. and heading back to the Rezidentura?

Joe: We can say Oleg has got serious stuff going on this season. It’s going to be a really powerful, interesting arc for him. It plays out on a couple of different continents, and it’s going to be very emotional and very intense with his family and with his colleagues at the Rezidentura. Every year his story gets more important.

We’ve seen more flashbacks to the pasts of Elizabeth [Keri Russell] and Philip [Matthew Rhys]. The idea of reassessing where you came from and how that informs your present-day existence, do you think that’s a bigger deal this season?

Joel: I don’t know that it’s a bigger deal, but it’s certainly something we’ve been talking a lot about. Certainly this is a season where the pressure is rising, and when pressure rises, whether you repress its sources or you express its sources — they’re going to be revealed. They’re going to come out somewhere.

Joe: In season one, season two, and to some degree in season three, for every episode, we used look at it and say, “What’s the marriage story, and what’s the spy story?” This season, we didn’t do that. We didn’t have to — the stories came along in a way that was a little more organic and didn’t require it. I think the same is true of the flashbacks. In the first couple seasons, we would always have the question, “Do we do a flashback here or not? Do we need this flashback to tell the story?” That was never a question this season — the flashbacks had organic places where they dropped in naturally. But I think the final tally of flashbacks, at the end of the season, will probably be average.

Philip in particular is under this kind of pressure that’s forcing him to confront it to almost survive — not physically survive, but emotionally survive. The searching that he’s doing is bringing up the memories. We’ve always said these are such non-self-aware, non-introspective characters, but Philip is in fact becoming somewhat introspective.

And it seems as though Paige is being trained into operating as a secret agent, whether or not anyone overtly wants that to happen.

Joel: We have this great line that we’ve been saying, that she’s being trained to be a member of the Jennings family.

Joe: She’s being recruited to be their daughter. She grew up knowing how to do it without having to learn it because she was in it.

When does Paige get to wear a wig?

Joe: Don’t get her started. Holly [Taylor, who plays Paige] wants to kill people.

Oh my!

Joel: Yeah, I know.

Joe: Today’s youth!

Will we see more of Dylan Baker’s William coming up?

Joel: Absolutely. He’s got a big arc this season.

Can you comment on whether Margo Martindale will be returning as Claudia?

Joe: You’ll see more of her. We love Margo and we love that character.

You have said that you view this season as the season that marks the end of the second act of a three-act play. Is that what you’re thinking about as you are beginning to work on season five? [Note: An “Americans” renewal is expected but has not yet been officially announced].

Joel: There have been some big transitions along the way, and Joe and I are now talking about what will ultimately be the most satisfying end, and how we want to play that out. Whether that plays out over the course of five seasons or six seasons — I think we’ll be figuring out over the next couple weeks. But given how slowly we moved through story [thus far], who knows how long how long you’ll keep asking us that question. But I think we can all rest assured that this series will not end abruptly.

Joe: I think we’ll know soon. I think we’re awfully close to figuring it out, and it’s such a nice feeling to have that discretion as the storytellers — it’s just great.

Is your sense from FX that if you need one season, you’ll get one, and if you need two seasons, you’ll get two?

Joel: Yes. I think we’re pretty much in that position, and it’s an unbelievable luxury, and it says an awful lot about FX.

More and more this show seems to be about, can Philip and Elizabeth save their marriage or can they save their children? It just doesn’t seem like they can do both. To me, that’s the big question that hangs over the endgame of the series.

Joe: Honestly, we worry about both. I don’t necessarily see it as either-or. I think we tend to see both of those things at various levels of crisis. In other words, it’s possible lose both.

Joel: They do live in a world of real consequences.