Henry Cavill's Warhammer 40k Series Writer Makes One Story Adaptation Way More Likely

Published Aug 1, 2026, 8:30 AM EDT Zoë Miskelly is an editor and second in command for Screen Rant's Movies team, having covered the entertainment industry for almost 10 years now. Zoë's love of superheroes and all things Marvel & DC started out in childhood, and has blossomed into a career getting to talk about some of the biggest and best movies and shows of all time, having previously focused on comics while working at WhatCulture. The reveal of the writer who will be bringing Prime Video's Warhammer 40k series to life has primed the adaptation even better to take on one celebrated story set in the mythos. While the Warhammer 40k franchise has some expansive lore that has been intricately detailed over the course of the decades, most of this has been contained to the world of books and reveals placed within the guides for the beloved tabletop game, though Warhammer+ does notably contain some on-screen releases. However, 40k is set to come to the world of streaming in a bigger way going forward, with Prime Video having announced plans for a Warhammer 40k series, and with Henry Cavill being confirmed for the Warhammer 40k cast as well, thanks to the actor's fame and also his repeatedly expressed enjoyment of the wider franchise and its history. Excitingly, the update about one famous writer who is also now joining the Warhammer 40k adaptation's team makes it all the more likely the series can and will adapt one of the franchise's best narratives into a new format, breathing fresh life into it once more - even if this may end up being something of a plot twist to those expecting something like the 40k setup story and prequel known as the Horus Heresy to be adapted here instead. The Warhammer 40k Series' New Writer Is Officially The Perfect Excuse To Adapt One Beloved Book Story The latest news about Prime Video's upcoming sci-fi series is that horror scribe Mike Flanagan is set to write the Warhammer 40k script, using the talents the creator has honed via writing the likes of Gerald's Game, Doctor Sleep, The Haunting of Hill House, and Midnight Mass. Of course, this backdrop bodes well for the franchise by itself in terms of showing Flanagan is skilled at his craft - and in adapting book worlds on-screen, as we can see with a number of the projects he's been involved with over the years. That said, the specific trajectory Mike Flanagan's career has taken over the years is also promising in terms of what it suggests may be most viable for the Warhammer 40k series in terms of drawing fully on the writer's areas of expertise. While it does seem Flanagan could create an engaging story focused on just about anything, his history of writing about more grounded humans facing off against supernatural threats that challenge their perception of reality alongside their spirit does align nicely with one of the most praised Warhammer 40k book series of all time: namely, the Eisenhorn series. Though Gregor Eisenhorn is still more battle-hardened and savvy than most conventional humans in the 40k series - as a member of the Inquisition, who hunt out the Xenos and chaos threats humanity faces amongst the galaxy - he is notably less hardy in many regards than the likes of the conventional Space Marine, and the series leans on this fact to make you fear for the life of Gregor and the allies he picks up over the course of the series. Similarly, the Eisenhorn series revolves around its titular protagonist slowly growing to learn more and more about the nature of the universe and the more horrific inhabitants that lie within it, and increasingly delving into the supernatural side of Warhammer 40k's lore from the perspective of someone without the Space Marines' genetic mutations to help them survive. This makes it all the more fitting a match for Flanagan's areas of expertise, and makes it a potential golden pick for the Prime Video series in terms of introducing viewers to the world - as indeed the Eisenhorn novels are often recommended as a perfect starting point for readers. Warhammer 40k Adapting The Eisenhorn Omnibus Would Be The Perfect Start For A Full On-Screen Franchise The recommendations that new Warhammer 40k book fans pick up the Eisenhorn series makes a lot of sense, since the omnibus takes readers across the galaxy, introduces them to a wide range of factions, and underlines the dangers any ordinary person faces amongst the stars in this franchise. Perhaps most importantly, they're also a lot of fun, and balance explaining technical details about how the world works alongside providing plenty of larger than life action scenes, and a roster of endearing characters. With this in mind, the Warhammer 40k series taking a leaf out of these books in a literal sense would appear to be within its best interest, even if it would mean drastically fewer Space Marines than the franchise is often centered around. That said, depending on what starting point the series picked, it could still ensure these faces of the Warhammer 40k franchise were in the adaptation aplenty, since some parts of the overarching Eisenhorn narrative still feature them prominently all the same. Given the Eisenhorn series also has plenty of spinoffs and connections to the wider world of Warhammer 40k galore, there would be many worse choices for the Prime Video adaptation's story, particularly with a talented writer like Mike Flanagan on hand to ensure the original source material is done justice on-screen.