"Every lie we tell incurs a debt to the truth. Sooner or later, the debt is paid." This line from Sunday's final episode of HBO's searing Chernobyl — spoken by the doggedly candid scientist Valery Legasov (Jared Harris) — speaks to the heart of the miniseries, which is both a riveting chronicle of one of the worst nuclear disasters in history and a morality play about the cost of a cover-up.

As depicted by creator Craig Mazin throughout the five-part project, the devastating 1986 explosion at the Chernobyl power plant was the result of a series of lies told by self-serving bureaucrats in service of a corrupt and incompetent government that prioritized its public image above the safety of its own citizens.

While this story is deeply specific to the Soviet regime, it also resonates in powerful and uncomfortable ways in modern America. Legasov and his colleagues — politician Boris Shcherbina (Stellan Skarsgård) and nuclear physicist Ulana Khomyuk (Emily Watson), the show's only fictional character — are forced to constantly defend the truth against powerful people who willfully deny scientific fact, even as it stares them directly in the face. For Mazin, the relevance of this infuriating dynamic was a major reason why the story was worth telling.

"This is in us, a certain sense of denial, a certain sense of groupthink," he tells The Hollywood Reporter. "This is not something that sits on one party line or the other. We've seen it in all permutations throughout history, and at the core of it is a certain insistence that what we want to be true is now true, and what we don't like is now false. That's not serving us well, and it has never served us well."

Below, Mazin talks with THR about Chernobyl's slow-burn success and unexpected memes, the storyline he left out because it felt "too Hollywood" and his plans for a follow-up.

You end the show on Legasov acknowledging, in voiceover, that the scientific search for truth is often undermined by the fact that people simply don't want to hear it. That feels pretty timely. Why did you wrap up on that note?

My personal belief is that there's not much value in showing things from the past that have no relevance to today, or failing to connect some kind of dotted line to where we are today, because otherwise it just becomes homework. What compelled me about the story of Chernobyl more than anything else was something very universal. Yes, Chernobyl happened because in many ways the Soviet system was deeply corrupt and evil, but the Soviet system did not arrive to us from some other planet. It was devised by humans. This is in us. A certain sense of denial, a certain sense of groupthink — this is not something that sits on one party line or the other. We've seen it in all permutations throughout history, and at the core of it is a certain insistence that what we want to be true is now true, and what we don't like is now false. That's not serving us well, it has never served us well. We need to ask ourselves why we feel entitled to say to scientists, "We actually think the climate isn't changing." Or "I think vaccines might cause autism." We can say that all we want, but it's not true, and it costs us. I want everyone who watches this show to consider how they themselves are complicit in a kind of conspiracy against truths that are uncomfortable.

Courtesy of HBO

The show has really gathered steam through its run — it was critically well received from the start but gradually built a devoted audience. Why do you think it has resonated so much?

I'm a big believer in the old-school way of releasing television. It's not to say that other platforms aren't making great shows, but there's something about just dumping it all down at once that I think, honestly, cheapens it a touch. It also steals any chance for a kind of spreading, and a person-to-person encouragement, where watching it becomes a communal thing. Chernobyl started well, but each week it grew, which is kind of not the way it normally goes, and we hit a critical mass as we headed into our fourth and fifth episode.

Have there been any reactions to the show that have surprised you?

Yes. I was very nervous about how the show would be received in Eastern Europe, in Ukraine and Belarus, in Russia, or any of the former Soviet Republics, and it's been fascinating. By and large, the overwhelming response from people has been just incredibly gratifying. They recognize that we made this with love and respect for them, and that we tried our hardest to get the details right, which I think from their perspective Western productions often either fail to do, or don't try to do at all. I did expect — and my expectation was rewarded — a certain level of propaganda from the Russian government, and after all, the man who runs that government is ex-KGB. They're putting out their own Chernobyl narrative, which is I think is based around a KGB officer trying to stop a CIA officer from doing something, and OK, sure, I figured that was coming, I get it.

I've also just been surprised by the strength of reactions from people on all sides of the political spectrum. There are people that missed the point, because they want to see this as a condemnation of people on the right who can't deal with science, and then there are people on the right who think it's entirely a condemnation of Soviet communism and socialism. What we're getting at is something that's a bit more universal and human than "Your side bad, my side good."

What was your biggest writing challenge?

Oh, for sure it was the trial sequence in the fifth episode. I had a lot of plates to spin at once, but the biggest challenge was I needed to explain something that's complicated; it's nuclear physics and power plant engineering. And I had to figure out a way to explain this to people because I'm not gonna not explain it — that's not me! I need people to know. So I worked really hard, and Jared, too, the two of us really went through that stuff line by line to make sure it was clear and there weren't any extra unnecessary things, but that we weren't leaving anything important out. either.

Courtesy of HBO

The red and blue cards were a nice visual way out of that conundrum.

Yeah, because if you're really into it and you have a predilection for science, you can follow it on one level, and if it's not your jam, you can at least look at colors and you get the point! More red is this, and more blue is that, and you can see what's going on in the reactor. I come out of comedy, where the thought of boring people is just horrifying, and losing an audience is your flop-sweat nightmare, so I just wanted to make it fascinating for everybody, as best I could.

The show is unflinching in its depiction of the physical effects of radiation poisoning. Was there anything you left out or were asked to leave out because it was too much?

Yeah, we had to be really careful in episode three when we showed the final stage of Vasily Ignatenko's body. It was the most extreme thing that we showed, and our makeup and prosthetic designer Daniel Parker did a brilliant job — so brilliant, in fact, that there was a concern that we lingered on it a bit. HBO was so supportive and so great, and Kary Antholis, who was the head of HBO miniseries when we were making the show, said, "You know, can you just shorten that shot? Because it feels like you're forcing us to look at this, like you're almost proud of it." I did not intend that, and that's not what we want at all. Sometimes you lose sight of those things, because you watched the prosthetics being built, and then you don't quite get how impactful it is. So we shortened that shot by quite a bit, because the last thing we wanted was to feel like we were trading on this man's sad fate for sensationalist points on a TV show. What we wanted was for people to see the truth of what happens, but we didn't want to feel like we were exploiting it. Those were the things we were dealing with all the time, because that man was a real person, and his wife is still alive, and the last thing we want to do is show anything other than total respect.

Was there anything else major that you filmed and omitted?

We shot a sub-story about Dyatlov, Paul Ritter's character, which touched on his history. Chernobyl was not Dyatlov's first nuclear disaster — he had actually been involved in another one years earlier, when he was a nuclear engineer at a submarine base. He received a pretty steep dose of radiation, a dose that theoretically could have killed him. It didn't, the guy was tough, but his son died about a year later of leukemia, and there was an implication that whatever contamination Dyatlov experienced he may have brought home with him and it may have impacted his son's health. From a writing point of view, if you have some backstory that helps explain a character's motive, or creates sympathy for an unsympathetic character, it's generally seen as a useful thing. But I just ultimately didn't feel like it was justified. It felt like I was stretching. I could make the case [for keeping it], but it felt a little Hollywood. Ultimately, when we looked at the cut, we didn't need it.

The show's popularity online is really striking — there are a lot more Chernobyl memes out there than I expected! What do you make of that?

(Laughs.) I think it's just how people show their love for something. When I was younger, I remember I was just obsessed with The Godfather, and there were like 1,000 Godfather parodies and lines like "We'll make him an offer he can't refuse" became this thing people would say, but nobody called them memes back then. When I was a kid, Welcome Back, Kotter was really popular, so we'd say all these stupid things that they say in the show, or Happy Days: "Sit on it!" Those were memes! I think it's how we show that we have fallen in love with something, and I take it all with joy. I don't think people are making light of anything that's serious; I think they're just saying, "We connected with this, and we love it."

Dyatlov's line, "Not great, not terrible," which is this moment of completely absurd denial, seems to be heavily memed.

Yeah, I have to give credit to Carolyn Strauss, who executive produced Chernobyl along with me and Jane Featherstone. Somewhere fairly early on in postproduction, she said, "You know what I love the most? When Dyatlov says, 'Not great, not terrible.'" She just zeroed in on that, it was like she knew, she was the original memer on that one. I don't know why she saw something in that line that for me was never a big thing, but she was right!

Courtesy of HBO

On the Chernobyl podcast, you briefly touch on the question of how a similar scenario would play out in the West, especially the moments where workers are effectively sacrificed for the greater good. Is that something you've thought a lot about?

The good news is we don't really have to worry about that, because it wouldn't have happened in the West. Our nuclear reactors don't explode, because they're built smartly, and carefully, and they are surrounded by containment buildings that are engineered so a plane can fly into them and they won't break. The RBMK reactor used at Chernobyl was just a terrible design, just flat-out. Too big, too unstable, uncovered, so we wouldn't have to deal with that problem. We can look at Japan — the way they dealt with Fukushima is impressive, and from that we can see that no matter what, there are going to be people that perform heroically and somewhat sacrificially, but they are also protected. When you see these guys going on the roof in Chernobyl, they're wearing these hand-hammered lead scraps that they've scrounged themselves and tied together with basically shoelaces, and that's something we don't do. We have resources and we would not do that, and they did it there. That alone, I just find breathtaking. The Soviet system was so bad, and the Soviet citizenry were so brave. They are remarkable people, and the things they have suffered and the things they have done through over the course of the 20th century, and today, is just amazing and inspiring to me.

Have you thought about a follow-up to the show? Is there another historical event you're interested in approaching in the same way?

I want to do a million things. If every day could be 70 hours and I didn't have to sleep, because I'm really just a student and I get fascinated with things. The one thing I can say is I'm going to continue in this vein of making a show about something that matters, that is real. I probably won't try and duplicate what I did with Chernobyl — I think down that road is failure. We've actually had a tremendous response from India, and a lot of people have tweeted at me from India saying, "Tell the story of Bhopal," which is an incredible story. That's something that I would encourage somebody else to tell, because I just don't want people to think, like, "Oh, he's just trying to play his hits." You have to write a new song! I know the next thing I'm going to do is something that is about now, and is about here, in the United States, and for better or for worse, I'll approach it with the same insistence on truth over narrative.

This interview has been edited and condensed for clarity.

Watch
'Chernobyl' Star Jared Harris On Emmy Nominations, Tourism at the Sight, Learning the Real Valery Legasov | In Studio