Henry Cavill’s Upcoming Sci-Fi Space Opera Series Writer Admits It's Been ‘Brutally Difficult’

Adapting thousands of years of lore and hundreds of novels presents a daunting challenge for the filmmaker

Mike Flanagan has spent years bringing some of horror's most beloved stories to the screen, from Stephen King's Doctor Sleep to Netflix's The Haunting of Hill House. His latest King adaptation, Carrie, has earned rave reviews and is dominating streaming on Prime Video, but the filmmaker's next major undertaking might be his most daunting yet: bringing the sprawling science-fiction universe of Warhammer 40,000 to live action.

Speaking on The Process Unlocked podcast, Flanagan described the Amazon project, which he's developing alongside star and executive producer Henry Cavill, as feeling like he's “climbing my adaptation Everest.”

The challenge, he explained, is figuring out where to begin with a franchise that has accumulated decades of lore, hundreds of novels and thousands of years of fictional history, pointing to the franchise's enormous cast and sprawling timeline.

“These are novel lengths. These are not small. But there are so many characters. It takes place over so many thousands of years. There's so much there,” he said. “The challenge is how do you get in? That's really a brutally difficult adaptation, but it's been so fun for it.”

What we know about the Warhammer 40,000 series

Amazon's live-action adaptation is being developed with Cavill, a longtime fan of the tabletop franchise, attached to star and executive produce. Games Workshop confirmed in a July financial report that initial outlines had been completed and Flanagan was expected to move on to writing scripts. The company has cautioned that its screen adaptations will take years to bring to market, and neither a release date nor specific storylines for the live-action series have been announced.

Flanagan is no stranger to adapting dense fictional worlds. He's also developing a television adaptation of King's The Dark Tower, a fantasy saga that spans multiple novels and connects to the author's wider fictional universe. But Flanagan said King's approach to introducing readers to that world makes it easier to find a starting point.

He pointed to the opening of The Gunslinger, the first Dark Tower novel, which begins with a simple premise: a gunslinger pursuing a man in black across a desert. King gradually builds out the larger mythology from there.

“Seventy percent of my job is done for me by Steve,” Flanagan said of adapting King. “Warhammer is not like that.”

The Warhammer 40,000 universe, created by Games Workshop, takes place in a brutal far future where humanity faces alien civilizations, demonic forces and seemingly endless warfare. Its stories span novels, tabletop games, video games and other media, leaving Flanagan with an enormous amount of material to navigate.

Flanagan's horror background could suit a universe known for its grotesque monsters, religious fanaticism and cosmic terror. Beyond Warhammer 40,000, his upcoming projects include DC Studios' Clayface and a new Exorcist film, while his Dark Tower adaptation remains in development.

For now, the biggest question is how Flanagan will distill Warhammer 40,000's enormous mythology into a story that works for longtime fans and newcomers alike. As his comments make clear, finding that entry point is one of the most difficult parts of the job.