After decades in development hell, Stephen King’s eight-book The Dark Tower series will finally make its way to screens on January 13, 2017, courtesy of Sony Pictures, writer-director Nikolaj Arcel, and stars Idris Elba and Matthew McConaughey, whose participation was officially announced on Monday by none other than King himself. It’s news that’s been greeted with both excitement and trepidation, both because fans have been down this road before—most recently, with Ron Howard’s ambitious plan to adapt it as a collection of films and a TV series starring Javier Bardem—and because, according to King and Arcel, the forthcoming movie (co-written by A Beautiful Mind scribe Akiva Goldsman) will not begin with the first novel, but instead will start “in media res” (i.e., in the middle), and will largely be set in the present day. Oh, and plans for the rest of the franchise remain up in the air. To put it mildly, die-hards’ mounting anticipation is matched by dawning panic.

For those who’ve never ventured to Mid-World, a magical, dying quasi-Old West where much of The Dark Tower’s action takes place, the fierce, feverish responses to these production announcements must sound more than a bit perplexing. Yet rest assured, they’re justified by the fact that King’s magnum opus, which began with 1982’s The Gunslinger and ended with 2004’s The Dark Tower—and then received an additional, interlude episode in 2012 with The Wind Through the Keyhole, not to mention comic-book prequels and adaptations—is something like a culmination of the author’s prolific work. A sprawling fantasy saga that’s equally indebted to Spaghetti Westerns, The Lord of the Rings, Star Wars, King Arthur, and Robert Browning’s poem “Childe Roland to the Dark Tower Came,” it’s an odyssey that combines myriad literary and cinematic genres, all while also intersecting with people and places from King’s prior books and shorts. It’s a story about a search for the nexus of all universes that, at heart, is the nexus of King’s own oeuvre.

While that description might make The Dark Tower sound like a daunting undertaking, King’s series is easily accessible to newbies, thanks in large part to the fact that, structurally, it gradually inflates from something lean into something grand. The Gunslinger opens with the line, “The man in black fled across the desert, and the gunslinger followed,” and its opening installment is just that—a chase, in which an ancient Clint Eastwood-style cowboy knight named Roland Deschain (to be played by Elba) treks across a vast Mid-World desert in pursuit of the Man in Black (to be embodied by McConaughey), his first priority on his larger mission to reach the Dark Tower. Roland seeks the Tower in order to set his crumbling world right, and along his journey, he encounters—and then loses—a boy named Jake Chambers who, it turns out, has somehow reached Mid-World from Earth, circa the early ’80s.

In subsequent novels, Roland’s quest finds him teaming with more compatriots from our world—NYC junkie Eddie Dean, and wheelchair-bound Susannah Dean, who has a darker, dangerous dual personality—and venturing through the gone-to-seed towns, cities and wastelands that comprise his home. He encounters titanic robot bears, evil sentient monorail trains, and other assorted crazies, many of whom boast ties to King’s other tales, none greater than the Man in Black, who under the name Randall Flagg functioned as the hellish villain of The Stand and The Eyes of the Dragon (among other King yarns). It also repeatedly returns to Earth, where protecting a rose in an abandoned NYC lot may be the key to saving all universes, and—as befitting a story so deeply rooted in King’s own canon—eventually finds Roland and his crew (known as a “ka-tet” in Mid-World’s archaic “High Speech” parlance) joining forces with none other than King himself, who becomes a central character during the final books.

Replete with novel-long flashbacks (see: The Dark Tower IV: Wizard and Glass), and brimming with of one electric centerpiece after another, it’s an immense, otherworldly adventure. And especially in the last three books, which were written in a flurry in 2003 and 2004—when the author, post-near-fatal accident, felt compelled to complete the tale while he still could—the franchise’s mythological scope expands to almost delirious levels. Yet what makes it so special is King’s ability to ground his out-of-this-world material—and its synthesis of so many disparate fictional inspirations—in unforgettable characters. Roland, Eddie, Susannah, Jake (whose death doesn’t keep him from continuing to be an integral player), and even their pet billy-bumbler Oy (a badger-raccoon-dog creature) are so richly drawn, and their various intertwined issues are so fully developed, that The Dark Tower pulls off the difficult trick of being both awash in spectacle, and yet ultimately about the emotional/psychological/spiritual/moral dilemmas of its main characters.

Given the sheer enormity of The Dark Tower, it’s no surprise that past luminaries attracted to adapting it (not only Ron Howard, but J.J. Abrams as well) have found themselves stymied. With its disparate, often-outlandish locales, its magic and supernatural incidents, and its not-always-human characters, the series demands a big-screen commitment akin to that given to Peter Jackson by New Line Cinemas for The Lord of the Rings—except that any likeminded version would require not three films, but something closer to seven. That’s why when Howard proposed shifting some of his adaptation to television, the idea (however unconventional) made a crazy sort of sense, since the only way to genuinely translate it would be via a serialized small-screen show à la Game of Thrones (with an enormous production budget to match).

While this week’s adaptation news doesn’t preclude such an idea from eventually developing, the first dramatic iteration of The Dark Tower will find Elba wielding Roland’s trusty firearms while hunting down McConaughey’s Man in Black in a movie that, by all accounts, will be primarily rooted in events from The Dark Tower III: The Waste Lands. To be sure, that chronologically screwy tack raises far more troubling questions than it answers. But for now, at least, fans can rest easy in the knowledge that the film’s casting is strong (Elba and McConaughey are ideal leads for such a venture) and that, if nothing else, the years of speculation and suspense are coming to a close. For better or worse, Roland’s epic journey is about to begin.