The atomic bomb research facility in Los Alamos, New Mexico, that devised the weapon that ended World War II was one of the nation’s best-kept secrets. Some outsiders, including geopolitical rivals, knew the Manhattan Project existed, but most of the American public remained completely unaware. The same, unfortunately, can be said of Manhattan, a 2014 TV series that won nearly universal hosannas from critics and was cherished by its viewers. If only there had been more of them.

Manhattan, sadly, was TV’s best-kept secret—a decade before Christopher Nolan’s Oppenheimer became a blockbuster by chronicling the atom bomb’s lead scientist. The show, set 70 years in the past, was just a few years ahead of its time, debuting right before the streaming era, when everything is available all the time and word of mouth can more easily power sleeper hits. Manhattan fell victim to the fact that it had to be sought out on an obscure network: remember WGN America…? Don’t worry, neither does anyone else.

Sam Shaw, now best known for the Stephen King–themed series Castle Rock, was Manhattan’s creator and showrunner, and his wife, Lila Byock (Watchmen, The Leftovers), was one of its writers. They have watched the cinematic debut of Nolan’s Oppenheimer with a sense of resignation, and even a little optimism. “If someone were to walk out of Oppenheimer and seek out Manhattan, I think that would be really a great outcome,” Byock says. “There’s obviously so many stories to be told about Los Alamos and about that moment in American history. There is room for many, many versions of it.”

The two seasons of Manhattan, spanning from the start of the research effort to the first nuclear test, known as Trinity, now streams for free on Tubi. Shaw had plans for at least four more seasons, with the actual dropping of the bombs on Japan in August 1945 happening at the midpoint, and the back half of the series focused on the new and even more dangerous conflict of the Cold War. “It still smarts that we didn’t get to tell the story in its fullness as we hoped,” Shaw says. “We actually had a lot of story that we were really excited to tell. The race against the Nazis, leading up to Hiroshima and Nagasaki, was fascinating, but it kind of felt like the vegetables that we had to eat to get to the most morally complicated story. And sadly we didn’t get there.”

For the first time publicly, the creative team behind Manhattan reveal what might have been—and also, what almost was. They detail unwritten story arcs as well as alternate casting considerations for some of the key roles, among them the pivotal part of J. Robert Oppenheimer himself. 

“When we were casting Oppenheimer, we went through a whole series of different ideas,” says Byock. “There were actually some rock stars we considered.”

She means that literally. “David Bowie was not available,” Shaw says. “I’m sure we talked about David Bowie, didn’t we?”

“We did talk about Beck,” Byock replies. “Do you remember if we reached out to Beck?”

“I don’t think we can say that we ‘reached out’ to Beck, but yes, it was something to think about,” Shaw says. “We wanted Oppenheimer to feel both like he possessed a certain undeniable charisma, a presence onstage, but also that he was playing a different instrument. He needed to feel alien—or other—in some ways. He stood out.”

Another casting possibility, they said, was Ebon Moss-Bachrach, who was then little known, but is now beloved as misfit cousin Richie on The Bear. “He’s got those eyes,” Byock says. But Manhattan’s Oppenheimer required aloofness and distance rather than the audience’s empathy. 

They also considered the same actor that Nolan chose for his own film. “A thousand percent, Cillian Murphy was on that list,” Shaw says.

Daniel London, best known as the caretaker of the psychic crime detectors in Steven Spielberg’s Minority Report, ultimately won the role, bringing an eerie detachment to the so-called Father of the Atomic Bomb. “Oppenheimer was a guy who was famous for being extremely charming when he needed to be, but also extraterrestrial in his erudition,” Shaw says. “And I think Daniel really got to that.”

Thomas Schlamme, an Emmy-winning director of The West Wing, who directed the pilot and four other episodes of Manhattan, recalls how he guided London toward Oppenheimer’s chilly demeanor. “He looked like Oppenheimer. It was uncanny. So first, I was trying to release him of that,” says Schlamme, who also executive produced the series. “I was trying to get to Daniel to see this doesn’t have to be an impression.” 

The most important part of the performance was conveying how Oppenheimer existed on a different wavelength from the scientists he led. The trick, Schlamme felt, was to have London not always pay attention. “I was kind of leading him [to see] it doesn’t really matter what somebody is saying to you,” he says. “You have made some decisions in your life that supersede the ability to listen and to be as present as you need to be. You can’t ‘play mystery.’ You need something active in that process. So the active nature of it was: Actively don’t listen. Actively silence yourself.”

In those scenes, London’s thoughts are elsewhere as the scientists of the Manhattan Project beseech his guidance and attention. That’s how Manhattan captured the spirit of Oppenheimer.

Most of the characters in the series were fictionalized versions of the real-life figures who built the atomic bomb. John Benjamin Hickey played Frank Winter, the Don Draper of Los Alamos, a physicist who dreads the destructive potential of “the gadget” even as he works fervently to complete it. Olivia Williams was his wife and conscience, Liza, a botanist who is kept in the dark about the true nature of his work. They were the more weathered and cynical version of another couple at the facility, ambitious young scientist Charlie Isaacs (Ashley Zukerman) and his lonesome wife, Abby (Rachel Brosnahan), who falls in love with the housewife next door (Carole Weyers).

Many of Manhattan’s stars were relative newcomers at the time who went on to success elsewhere. Brosnahan became the star of The Marvelous Mrs. Maisel and has been cast as Lois Lane in the next Superman movie. David Harbour, who was rival scientist Reed Akley on the series, went next-level as police chief Hopper on Stranger Things and Russian superhero the Red Guardian in Marvel’s Black Widow.

Katja Herbers, who played Helen Prins, the series’ lone female scientist, now stars in the supernatural crime series Evil. Corey Allen, whose Theodore Sinclair was the only Black scientist in the series, has gone on to appear in Mindhunter and Power. Michael Chernus, Manhattan’s lovable sci-fi-loving scientist Fritz, has also become a go-to character actor, with roles in Spider-Man: Homecoming, the Dead Ringers TV series, and Severance. 

Finally, Christopher Denham, who who played the duplicitous fictional spy Jim Meeks in Manhattan now appears in Nolan’s Oppenheimer—as real-life spy Klaus Fuchs.

Today, such a show might not be able to afford such a cast with the modest budget they were granted for Manhattan. “We love the show so much. We’re so proud of the show. But I will say, we didn’t have huge resources to make it, actually,” Shaw says. “We basically just built a world in New Mexico and shot it practically like we were building our own town. At times, we had to drag partners at the studio along with us.

“It also meant that we had to have incredible actors who were always prepared,” he adds. “So much of that is on Jeanie Bacharach, our casting director, who also cast The Bear and Mrs. Maisel. She’s absolutely extraordinary. And our production designer, Ruth Ammon, who just figured out how to build this world and make it look great.”

Manhattan did land a number of well-known recurring stars. The West Wing’s Richard Schiff turned up as a ruthless spy hunter, Home Alone’s Daniel Stern was a warm-hearted older scientist, and CSI’s William Petersen played the colonel overseeing the project for the US military. (Matt Damon plays that role in the Nolan movie.)

Most of the roles were fictionalizations or amalgams of real-life figures. Oppenheimer was the main exception, and just like Nolan’s movie, Manhattan delved into his personal controversies, like the mysterious death of his lover, Jean Tatlock (played by Florence Pugh in the film and Fiona Dourif in the series).

“Oppenheimer puts the umbrella of reality over the whole thing,” Schlamme says, calling him one of the “landmarks that grounded the piece in a certain way. I think it was really important that it wasn’t a fictionalized Oppenheimer.”

Manhattan’s second season finale concluded on the night of the Trinity test in New Mexico, which took place only a few weeks before the weapons were dropped on Hiroshima and Nagasaki, killing an estimated 199,000 people, most of them civilians. The unproduced next season would have ended with those detonations, and the rest of the show would have dealt with the literal and figurative fallout.

“To use a Hollywood cliché, it was a show with a ticking clock baked into the material,” Shaw says. “The third season was going to take place essentially in a week, beginning 48 hours before the dropping of the first bomb and leading to the dropping of the second bomb. Part of what the third season was going to reckon with was the moment when everybody else in this place becomes privy to the truth.”

“Many, many people who lived at Los Alamos during that time had no idea what was happening,” Byock adds. “Then they suddenly realized that they’d been complicit in this act of violence.”

A fourth season would have leaped ahead briefly time. “It was going to deal with what happens to all of these scientists and their families as they’re reckoning with the secrets that they’ve been keeping from each other,” Shaw says. “But also, what is it for them to suddenly become these celebrities and avatars of this new nuclear age and of this choice to have dropped the bomb?”

The scientists would have gone from ultra-secrecy to ultra-famous. “Oppenheimer, and a lot of the other scientists as well, were kind of paraded on a quasi USO tour,” Shaw says. “They were expected to represent to America and the world the righteousness of the choice that they’d made, even as a lot of them were wrestling with extremely complicated feelings about the bomb, its legacy, and their fingerprints on it.”

Shaw provides a loose sketch of what the season would have explored. “One other piece of the history that, to me, has always been incredibly harrowing is that in the early weeks and months after the bomb was dropped, there began to be rumors about these secondary effects of the bomb, about a radiation sickness that might be associated with it,” Shaw says. “And there was a huge campaign on the part of the American government to deny the existence of radiation sickness and to prove that those reports were a fiction that was being promoted by the Japanese government in order to exact more favorable conditions of surrender.

“And in fact, it fell to a bunch of scientists, some of whom were the architects of the bomb themselves, who had been flown out to Japan and were looking at the wreckage of this thing that they’d brought to life, that previously existed only as a bunch of equations on chalkboards,” Shaw adds. “And they are charged with proving the fact that radiation sickness is a fiction, even as some of their colleagues back at home are getting sick and dying.”

One of these researchers would have been Williams’s botanist. “A lot of the stories that we told with Liza Winter in the first two seasons were really laying the groundwork for her character to take center stage in a different way in that season as she goes to Japan and begins investigating this mysterious new illness, essentially trying to call attention to what has happened,” Byock says.

The fifth and sixth season would have been firmly entrenched in the Cold War. “The makeup of Los Alamos changed pretty dramatically on the other side of World War II, as you would expect,” Shaw says. “Very quickly a lot of folks left; they couldn’t get out quickly enough. And then others stayed and still more came. You can imagine what the sort of political and social dynamics in that place feel like when the new recruits are actually attracted by the idea that they are going to be working on even more complicated and destructive weapons of war.”

In those later episodes of the series, scientists who were complicit in the originating the atomic bomb finally rise up against newer developments that would have created even more devastation. “In those years of the Cold War, as there was enormous pressure to develop a different kind of bomb—what they were calling the ‘Super Bomb’—to become the hydrogen bomb,” Shaw says. “There was a conspiracy of scientists, some of whom had been the most vocal proponents of the need to build the atomic bomb, who were trying to subvert plans to develop the Super Bomb. And all that was very much a story that we were interested in telling.”

These latter seasons also would have featured “congressional hearings when it emerged that the secrets of the bomb had been stolen,” he adds. But by the end of the show, the story would have returned to the desert of New Mexico where it began.

“The very clear end point of this series was a moment that always fascinated me—the moment when all of those gates, all the barbed wire, all the security around Los Alamos was finally torn down,” Shaw says.

While he didn’t offer specifics about what might have become of each of the characters, this actual historical incident would have drawn Manhattan to a close. “What was fascinating, symbolically, to all of us about that moment is it felt like the gates were no longer necessary because America had become Los Alamos writ large,” Shaw says. “The codes of secrecy and the ethos of self-preservation through violence that were born in that place had been blown across the country. And we were all the down-winders who had been infected with it.”