There have been several attempts to make a big or small screen version of Stephen King’s epic Dark Tower series. The rights are currently with Ron Howard, although at one point they were with J.J. Abrams. With big Hollywood players behind it, an author with a proven fanbase and the potential for a big summer tentpole action franchise, it seems like The Dark Tower should have been a slam-dunk. But there are several factors that work against it.

Please note that there are minor spoilers ahead for The Dark Tower.

1. The books are uneven

Of the eight Dark Tower books, two (The Wind Through the Keyhole and Wizard and Glass) are made up entirely of flashbacks, where the main narrative arc pauses and the hero tells a story. The Drawing of the Three has protagonist Roland stumbling along a beach meeting the rest of the main characters. Book six, The Song of Susannah is 400 pages long while book seven, The Dark Tower clocks in at a whopping 850 pages. The novels aren’t like Harry Potter where each has a distinct story that furthers the main story arc; they jump around and work more as one long, rambling novel with occasional breaks.

2. Where do you begin adapting it?

The books are fleshed out with a lot of flashbacks and stories that tell the reader more about the world it takes place in. There’s also a rather good companion comic book series that reveals even more about the history of the characters and of mid-world. But where is the logical starting point? Should a brief history of the gunslingers be included? Should the film start where the books do, at an almost random point in Roland’s journey, or earlier than that so the audience gets a better idea of what’s going on? There are many different ways it could be adapted and each way would produce vastly different results.

3. It’s intricately linked to Stephen King’s other works

Several characters from King’s universe pop up in the Dark Tower books, and even play major roles in the unfolding events. There are also hundreds of references to people, monsters, places and events from King’s vast backlist of novels. Fans would demand the inclusion of many of these, but they may prove alienating for the uninitiated. The novels also feature nods to the worlds of Star Wars, Harry Potter and Spider-man so there may be legal issues to work out too.

4. Stephen King is a character in the saga

How would this even play out on film? King himself turns up towards the end of the saga, as the heroes cross from their world into ours and discover that King is a kind of conduit for the events they are experiencing. Roland also finds his fate and well-being is inextricably linked to King’s. How awesome/weird would it be to have King playing himself? But if it’s not done right, it could come across as awkward and silly.

5. The Western Factor

Roland is, essentially, a cowboy. And cowboy movies don’t have a great track record. There’s definitely an audience for them, but they pretty much have to be Oscar bait to find that audience (think True Grit and Django Unchained). Otherwise, they’re expensive to produce and don’t have broad audience appeal (think Wild, Wild West and The Lone Ranger). While The Dark Tower goes beyond being simply a Western (it’s a post apocalyptic sci-fi/horror meditation on the nature of stories with a solid dose of high fantasy thrown in), the imagery is very much rooted in Clint Eastwood style westerns.

6. The Stephen King Perception Factor

While King has a huge fan base, there is an even larger number of people who are turned off by him. He has the reputation for writing violent horror, and while that’s only a part of what he does, there are people who will not go anywhere near his work.

7. The Stephen King Adaptation Factor

King adaptations haven’t had the best track record in terms of quality or box office. Mostly his adaptations are low budget TV movies or direct to DVD films that are uninspired and lazy. There are a few standouts like The Shining or The Mist (come at me, bro) but they are the exception rather than the rule. The best performing King adaptation of recent years was 1408, which made $130 million. See below for why that’s not good enough for The Dark Tower.

8. The Numbers

Let’s look at it from the point of view of the accountants that run Hollywood. Fewer middle-range movies are being made these days as studios attempt to make low-budget arthouse crossover hits, and uber-budget franchise movies. The Dark Tower would have to have a huge budget, at least $150 million for the first instalment and proabably more for the others. They would need a huge cast, expensive location shoots and special effects, huge production design and a global marketing campaign. For a movie to break even it needs to make back double its production budget (cinemas take about 50 cents for every dollar a movie makes) plus another $100 million or so to cover marketing costs. So the first Dark Tower movie would need a worldwide box office haul of at least $400 million to come out ahead, or $350 million, rave reviews and solid blu-ray sales to make it a good basis for a franchise. To put that in perspective, it would need to be at least as popular as Batman Begins, X-Men: First Class or the J.J. Abrams Star Trek movie. Bear in mind that those movies had a lot more awareness and cultural cachet than The Dark Tower does.

9. The Green Lantern Factor

Non-comic book audiences didn’t really know much about The Green Lantern when it hit screens and flopped a couple of years ago. The studio and the filmmakers had to spend a lot of time and money explaining the world and the concept before they could let audiences know compelling reasons why they should see the film. The Dark Tower is a similar proposition. Like Green Lantern its awareness is not high outside of its established fan base, and it has a complex world and backstory to explain before it can get to selling movie tickets.

10. It would take about a decade to do it properly

You’d be asking actors, filmmakers and the studio to commit to at least three big budget movies, probably more, spaced out over the course of several years. The production schedule on a film like this can stretch for two years, so the filmmakers would have to dedicate themselves to pretty much this exclusively. It would become the work that defined them, much as Batman has come to define Christopher Nolan and Lord of the Rings has come to define Peter Jackson. The filmmakers would have to really, really want to do it and be prepared to stake their careers on it.

And, as illustrated above, it’s a huge gamble.

This post was originally published July 10th at Momentum Books’ Blog.