TERRY PRATCHETT once described life as a film you’ve walked into ten minutes late, and whose plot you have to work out from the clues. It was announced last week that, after more than 70m books sold, translations into 37 languages and merchandise ranging from board games to cookery books, one of his “Discworld” novels was to be made at last into a feature film. A newcomer to Pratchett would be forgiven for feeling a little baffled: how could such a commercially successful series, matched only by “Harry Potter” and “Twilight”, have avoided the siren call of Hollywood for so long? The will-they-won’t-they saga of bringing Pratchett to the big screen is almost as long as the 41-strong novel series itself. In 1992, Pratchett was approached by an American production company about his novel “Mort”, a dark comedy about the skeletal, scythe-wielding figure of Death taking on an intern. (A fan-made graffiti painting of Death, based on the artwork of another book, “Reaper Man”, is above.) “We’ve been doing market research and the skeleton bit doesn’t work for us, it’s a bit of a downer,” Pratchett recalled the producers saying, “We love it, it’s high concept—just lose the Death angle.” The film went no further.

Over the years, the hopes of fans have been raised and dashed. Earlier this year, concept art surfaced which showed that Disney had been considering another “Mort” adaptation in 2010. The book that is now being adapted by the Jim Henson Company—“The Wee Free Men”—is a gleefully impious tale of a nine-year-old witch and her drunken, rowdy Scottish pixie clan. It has already been through the workflow at least once; Sam Raimi, an American director, was attached to it in 2006. The project fell through when it became clear that everything the book was against—following dreams, finding princes, neat endings—was exactly what film-makers had in mind for it.

One explanation for the Sisyphean back-and-forth might be just the fiercely anti-Disney, sceptical bent to Pratchett’s writing. Any book which has as its guiding credo the line: “If you trust in yourself…and believe in your dreams...and follow your star…you'll still get beaten by people who spent their time working hard and learning things and weren't so lazy” is going to find it tough to maintain its integrity once the studio has made it commercially palatable.

Or so we might have thought. But Hollywood is rapidly turning subversion of its own tropes into its chief box office asset. “Frozen”, a Disney princess story about the bond between two sisters that made more than $1 billion worldwide, cheerfully rewrote all the accepted kid-friendly rules about dreams and true love. It has ushered in an irreverent revisionist wave from “Into the Woods” to “The Lego Movie” that would comfortably incorporate a strong heroine uninterested in romance, much like “The Wee Free Men”’s Tiffany Aching. The irony and subversion powering Pratchett’s writing has never had a better time to flourish in Hollywood. Yet even with this change, Pratchett’s works resist easy adaptation. Much as Douglas Adams’s “The Hitchhiker’s Guide to the Galaxy” long resisted a film version (and even then produced a mediocre result), Pratchett’s authorial voice is hard to convey on the screen. Pratchett in particular relies on paratext—a novel commenting on being a novel. Reading him is to be endlessly second-guessed. The brilliance of a quip like “Give a man a fire and he's warm for a day, but set fire to him and he's warm for the rest of his life” lies in its subversion of expectation, but in a particularly literary way. Its force depends on the eye crossing the page, not a viewer watching images on a screen. However hard Hollywood now wishes to deconstruct its own clichés, it has a limited capacity to convey such metafictional tricks; it is hard to see “Discworld” working without some kind of narrator figure who could perform this function. Dealing with the authorial voice, especially one given to diversions, paratext and self-awareness, has always been a problem for Hollywood when attempting to adapt satirical novelists. “A Cock and Bull Story”, which features film-makers struggling to adapt Lawrence Sterne’s “Tristram Shandy” (an 18th-century novel so prone to digression that the narrator takes several volumes to reach his own birth), skilfully manoeuvred the problems of adapting a book about writing a book. They made a film about a film failing to get made, and in doing so, ingeniously translated the spirit of the original. Pratchett’s writing, too, is often about writing itself. If “Discworld” has a central theme it is that all the lies we tell ourselves, the stories and fantasies, have value in and of themselves. A talking skeleton can’t be written out merely because kids will be scared of it: the whole point is that humans young and old have always used phantasms and ghouls to talk about, and face, their fears. Pratchett's version of Death—humane, decent, occasionally befuddled—offers the hope that there is in fact nothing to fear out there in the dark. This "stories about stories" theme of “Wee Free Men”, and any adaptations that follow it, will be hard to render accurately on film. The signing of Rhianna Pratchett, the late author’s daughter, to write the script may yet provide hope; she, at least, is unlikely to sacrifice her father’s vision to the gods of market research.

In “Moving Pictures”, the tenth book in the Discworld series, a power-mad director announces that he wants “a thousand elephants” for one of his films. After a Herculean effort, someone actually manages to fulfil his insane request. Having moved a herd of elephants across several continents, he finds that the movie business has moved on by the time he arrives. Getting to the point where Pratchett’s impish style might find a place in Hollywood has been a long journey—we can only hope it will have time to find its voice before the trend passes.

Correction: An earlier version of this article stated that the graffiti pictured is of a character named “Mort”. It is, of course, “Death”. Sorry.