Neil Gaiman is nervous.

The acclaimed author has seen his work adapted into films, TV shows, and even operas, but for the first time, he’s taking the lead himself, serving as the showrunner of the upcoming Amazon series Good Omens. It’s his first foray into running a TV show, and he’s adapted his and Terry Pratchett’s cult 1990 novel into a six-part series, following an angel named Aziraphale (Michael Sheen) and a demon named Crowley (David Tennant) as they attempt to avert the apocalypse.

Gaiman has put all his book-writing on hold for the last several months to focus on showrunning, and now, he’s about to walk into a meeting with a bunch of Amazon executives to discuss the show. It’s a meeting he’s been anticipating for a while.

“I got all gloomy the other day, and my wife was like, ‘What’s the worst thing that could happen?’” he says. “And I was like, well, obviously, they will watch it and decide that this has been a waste of many tens of millions of dollars, close the entire project down, and nobody will ever talk to me again and occasionally it will be referred to as one of those strange, dark, awful things like Heaven’s Gate or whatever.”

He pauses. “But that probably won’t happen because most people seem to like it so far.”

And how could they not? The show won’t debut on Amazon until 2019, but it’s already one of the most buzzed-about series of the new year, thanks to its starry cast and tongue-in-cheek tone. It’s also been a long time in the making: Gaiman and Pratchett have been trying for decades to get someone to adapt the novel. (At one point, Terry Gilliam was attached to do a film version.)

Gaiman had never planned to make a TV version himself — and certainly not without Pratchett, who was diagnosed with Alzheimer’s disease in 2007. But it was an email from his co-author, written shortly before his death in 2015, that changed Gaiman’s mind.

“Terry never asked for anything in 30 years of friendship,” Gaiman explains. “He wrote me, ‘Look, you have to do this because you’re the only person with the same passion for the old girl as I have. You have to make this, and I want to watch it.’ And then he died fairly shortly after, which left me in this place where it was now a last request and something that I had to come through on.”

The result is six episodes that cover everything from the birth of humanity to the apocalypse — which Aziraphale and Crowley are trying very hard to prevent. Add in a misplaced Antichrist, a prophetic witch, and Jon Hamm as the archangel Gabriel, and you’ve got a rollicking but poignant doomsday farce that’s pure Pratchett and Gaiman.

Director Douglas Mackinnon has been jotting down Gaiman’s thoughts and musings on the series ever since production started, and EW got an exclusive look at his notes. Here, Gaiman breaks down those notes and explains how he’s shepherding Good Omens from page to screen.

Image zoom Amazon Studios

“While I have no doubt we will offend our share of people on this show, I feel we should always do it intentionally.”

“I think we were talking about casting Adam and Eve,” Gaiman explains. “Because in the very, very opening scene, we have Adam and Eve, and they’re black because we’re in Africa and we’re in the Garden of Eden, and of course Adam and Eve would be black. And that was one of those places where it’s like, if people are going to find this offensive, great. Let’s know that, and let’s own it.”

“The humour comes from normal people in strange situations and strange people in normal situations.”

“Doug grumbles about that, even now,” Gaiman says. “If you notice, the date on that is Christmas 2017, and he keeps saying, ‘If only you’d told me that five months earlier!’ And I was like, ‘We weren’t talking about it [then]!’ ”

But, he adds, it is true: Good Omens’ funniest moments all come from the idea of powerful entities in mundane situations and normal people “having to deal with a delirious reality of heightened, absolute madness.”

“Based on the novel Good Omens by Terry Pratchett and Neil Gaiman”

“It was frustrating as a writer because when I got stuck, I didn’t have Terry to call and say, ‘Hey, I’m stuck,’” Gaiman says. “And when I did something really clever and got unstuck, I didn’t have Terry to phone up and say, ‘Hey, I did this clever thing!’ But I was determined to make a Good Omens that Terry would’ve liked. And the only way that I knew how to make that was to make a Good Omens that I would like.”

And, he adds, he’s become much more protective over Good Omens than he ever was when someone wanted to adapt his own solo work.

“I was much, much, much, much more difficult than I ever would have been with one of my things,” Gaiman explains. “Because with my things, I tend to [react to changes by saying], ‘Oh, good! No, try it!’ Whereas with this, it was like, ‘People want to cut this scene?! But Terry wrote this scene! This scene is not going to be cut!’ And I got to be much more of a bastard.”

“Make us laugh, make us cry.”

The story itself is frequently absurd — think demons threatening houseplants and monstrous hellhounds transformed into tiny, scruffy mutts — but for Gaiman, it was important for the actors to always play things straight and root all the comedy in a place of real emotion.

“When I found myself getting sniffly a couple of times in episode 6, I said, ‘Okay, it’s working,’” he says. “If I — who am intimately familiar with this — am actually getting a little bit sniffly, then this thing is real.”

“Composure. Belief. Ego.”

“I have no idea what ‘composure, belief, and ego’ is,” Gaiman says with a laugh.

“I don’t want to lose any of the bits that make people happy.”

Gaiman says one of the most difficult decisions he’s had to make is what to cut and what to add when adapting a 400-page book into a six-part TV show. He’s deleted some plot points from the original book and expanded others, and a lot of the new stuff comes from discussions he and Pratchett had about a possible Good Omens sequel.

But ultimately, he says, the most important thing was making sure the TV show and the book capture the same emotions and themes — if not always the exact same plot details. (Although, he adds, fans of the book can expect more than a few Easter eggs in the show — like fake James Bond bullet holes on the window of a certain demon’s car.)