When Kit Harington entered the conference room, he had no idea what to expect.

The final season’s scripts had been emailed just a couple of days earlier, sending the Game of Thrones cast into a reading frenzy. Like millions of fans around the world, the actors had been waiting nearly a decade to learn their characters’ fates. The entire six-episode season arrived at once, protected by layers of password security.

Sophie Turner flew through her copies in record time, quickly messaging the producers her reaction. “It was completely overwhelming,” says the actress, who plays Sansa Stark. “Afterwards I felt numb, and I had to take a walk for hours.” Others, like Emilia Clarke (Daenerys Targaryen), first had to hurry home to get some privacy. “I turned to my best mate and was like, ‘Oh my God! I gotta go! I gotta go!’” she recalls. “And I completely flipped out.” She then settled in for a reading session with a cup of tea. “Genuinely the effect it had on me was profound,” Clarke adds. “That sounds insanely pretentious, but I’m an actor, so I’m allowed one pretentious adjective per season.” Peter Dinklage, meanwhile, broke his years-long habit of checking immediately to see if Tyrion Lannister survives. “This was the first time ever that I didn’t skip to the end,” he says.

Even showrunners David Benioff and Dan Weiss were uncharacteristically anxious, wondering how the actors would react to the climactic twists. “We knew exactly when our script coordinator sent them out, we knew what minute they sent them, and then you’re just waiting for the emails,” Benioff said.

The cast then journeyed to Belfast to gather in a production office for the formal read-through. By then, everybody knew the tale that was about to unfold, with two notable exceptions: Davos Seaworth actor Liam Cunningham (“The f—ing scripts wouldn’t open, the double extra security!” he grouses) and Harington, who outright refused to read anything in advance.

“I walked in saying, ‘Don’t tell me, I don’t want to know,’” Harington says. “What’s the point of reading it to myself in my own head when I can listen to people do it and find out with my friends?” So, yes: Jon Snow, quite literally, knew nothing.

Benioff and Weiss opened the proceedings by asking the cast to refrain from doing anything during filming or afterward that might reveal even the tiniest spoiler (“Don’t even take a photo of your boots on the ground of the set,” one actor recalls being told). And then, seated around a long table scattered with a few prop skulls, the cast read aloud the final season of Game of Thrones.

At one point, Harington wept.

Later, he cried a second time.

After the table read, the Game of Thrones cast spent 10 months filming just six episodes of television. But the season actually took far longer to pull off. GoT’s final chapters have been in the works for years. To better understand what’s ahead, let’s first go back to EW’s season 3 set visit and this never-before-revealed conversation with Benioff and Weiss…

The production camper was like many others on the set — barren, cramped, cold, utilitarian, with dirt on the floors from muddy boots tramping in and out all day. The showrunners sat on the same side of a tiny dinette booth while the wind coming off the Northern Ireland bay howled outside. They were already thinking about their final season, and it worried them.

During its second season, the fantasy drama averaged 10.3 million viewers across all platforms. That was enough to ensure they were eventually going to finish the series, yet that inevitability was also the problem. Because when they first pitched Thrones to HBO, they hadn’t exactly been honest. And now they were working every day toward a finale that was impossible to make.

“The lie we told is the show is contained and it’s about the characters,” Benioff said, which was at best half true. The epic fantasy was very much about its ensemble cast, but it’s also the least “contained” series ever made. “The worlds get so big, the battles get so massive.”

Author George R.R. Martin, whose series of novels forms the basis for Thrones, had revealed to the duo the broad strokes of how his Song of Ice and Fire saga secretly ends, including a description of an epic final battle that’s been teased from the show’s very first scene. But this climactic confrontation was miles out of reach for a series that cost about $5 million per episode. “We have a very generous budget from HBO, but we know what’s coming down the line and, ultimately, it’s not generous enough,” Benioff said.

So the producers had an idea: The final season could be six hours long and released as three movies in theaters — just like Martin’s best-known influence, The Lord of the Rings. It’s not that the duo wanted to make movies per se, but it seemed like the only way to get the time and money needed to pull off their finale. “It’s what we’re working towards in a perfect world,” Weiss said. “We end up with an epic fantasy story but with the level of familiarity and investment in the characters that are normally impossible in a two-hour movie.”

The flaw in this plan was that HBO is about serving its subscribers, not taking gambles at the box office. Behind the scenes, the network brass gently shot down the movie idea. But executives assured Benioff and Weiss that they would eventually have everything they needed to make a final season that was “a summer tentpole-size spectacle.”

Years later, the producers would strike a deal with the network to spend two years on a shortened season 8 that would cost more than $15 million an episode. You could say HBO made good on that promise from 2012, and the showrunners will happily give the network full credit. “They put their money where their mouths are — literally stuffed their mouth full of million-dollar bills, which don’t exist anymore,” Weiss quips.

But it’s probably more accurate to say that since season 3, Benioff and Weiss willed their ambitious final season into reality the hard way: by growing Game of Thrones into the biggest show in the world, a hugely profitable pop culture and merchandising sensation with more than 30 million viewers an episode and a record number of Emmys. Only with that kind of leverage do your towering ambitions begin to look like reasonable requests.

In fact, the GoT team was so successful that the biggest sticking point in the agreement was persuading HBO to halt the series. “We want to stop where we — the people working on it, and the people watching it — both wish it went a little bit longer,” Benioff says. “There’s the old adage of ‘Always leave them wanting more,’ but also things start to fall apart when you stop wanting to be there. You don’t want to f— it up.”

That concern — a constant desire to conclude the show on the strongest possible note — is something we heard over and over from the cast and crew when we visited the GoT set for the last time.