At least this can be said about The Dark Tower: It dares to be different. While most high-profile franchise starters try to do too much their first time out, this thing’s guilty of too little ambition.

After years of being in development hell, the adaptation of Stephen King’s sprawling eight-book Western fantasy series has been distilled to a mediocre action film (* out of four; rated PG-13; in theaters Friday) with uninspired battles and iffy special effects. What could have been the next Game of Thrones or The Lord of the Rings is instead more akin to a 1990s Steven Seagal movie (and not one of the good ones).

The lone highlight is its hero: Idris Elba oozes a winning sense of stoic gravitas as Roland Deschain, a gunslinger of Arthurian-like legend from a rough-and-tumble parallel landscape called Mid-World, whose journey to avenge the death of his father and kill the dangerous Man in Black (Matthew McConaughey) brings him to New York City.

Matthew McConaughey, Idris Elba face off in Stephen King's nearly unadaptable 'Dark Tower'

However, even poor Roland is stuck playing sidekick/mentor to Jake Chambers (Tom Taylor), a troubled teen who dreams of the Man in Black (which sounds a lot cooler than his real name, Walter) and of a large black tower. The gigantic structure stands at the center of the universe, and because it’s foretold that it can be toppled by a child’s mind, the Man in Black kidnaps youngsters and uses them to attack the tower. And because Jake’s “shine” is more powerful than most, ol’ Walter is in a hurry to have the kid be his latest weapon.

King nerds have plenty of inside references to spot, from a picture of the The Shining’s Overlook Hotel on a desk to a toy-box version of Christine’s killer car. And there are Easter eggs aplenty from the Dark Tower novels, including several pointing to the ultimate big bad from the books, the Crimson King, and the mysterious Sombra Corporation.

But instead of weaving those into the narrative in any real way, director Nikolaj Arcel’s movie just skims the surface of the Dark Tower mythology. The dusty geography of Mid-World, its creatures and personas from the books are seemingly put aside to spend more time in Manhattan, which does at least serve up some amusing fish-out-of-water moments as Roland shows Jake the way of the gunslinger.

The six-shooting protagonist digs hot dogs and Cokes, though McConaughey is pretty much chewing all the rest of the scenery as the over-the-top Man in Black. He’s devoid of his usual charm, and what’s left is a walking, talking nihilistic bore in a dark coat.

Matthew McConaughey endorses Mahershala Ali as a 'great fit' for HBO's 'True Detective'

So much potential in terms of star power and source material goes to waste simply because it seems like the filmmakers couldn’t figure out what movie to make. Dark Tower tosses out a lot of plot threads that never go anywhere, and even the ending is rushed, like somebody forgot to study for an essay test and then has to B.S. his way out of a failing grade.

Make no mistake, though, this is a fantastical faceplant, and though Elba tries his hardest, what could have been the tale of an iconic gunslinger is a big miss.