It was obvious at a Wednesday night screening of Dark Tower, the dreamed-of-for-decades screen version of Stephen King’s hybrid epic fantasy-Western series, that critics weren’t buying it.

And granted, there was a lot not to buy. Director Nikolaj Arcel’s cinematic interpretation (“adaptation” is a tricky descriptor for a bunch of reasons) of King’s series is a wildly ambitious attempt to take a sprawling story that spans many characters and multiple universes and turn it into an urban fantasy set mainly in New York City.

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Except for King’s main character, Idris Elba’s Roland the Gunslinger — who isn’t even the main character of this movie — the other film characters are all composites of multiple characters from the book series. Except for the broadest central plot point — Roland pursues a man, played by Matthew McConaughey, who wants to destroy the Tower that keeps our universe and many others in balance — King’s ideas have been largely swept aside for a strange fusion of science fiction and Weird fiction disguised as a Young Adult fantasy.

Yet for all of this, Arcel’s film is fun, loving, scary, and often as genuinely compelling as it is wildly misguided. The Dark Tower may be a terrible, even baffling version of Stephen King’s The Dark Tower, but it’s highly enjoyable as a cinematic King fanfic. Here are four things you need to know to prepare for the journey.

1) It’s best to think of The Dark Tower as a new Stephen King story rather than one we know

For so, so many reasons, a reasonably faithful film version of all eight books of The Dark Tower was never going to happen. (Spoilers follow for the Dark Tower book series.)

Even if all of the complicated plot and character arcs and narrative side-quests and ultimate battles could have fit into the film’s remarkably slight 95-minute timeframe, the fact is that the Dark Tower book cycle is essentially unfinished. Fans don’t know what the “ending” of Roland’s quest looks like because King, intentionally, never wrote one. Instead, he revealed that the stories’ events are cyclical and have happened many times before. He also implied that the “next” time around could be the quest that finally succeeds and breaks the looping cycle.

Here end the spoilers.

In the new film, the key to that success lies with a boy named Jake (Tom Taylor), a psychic teen living in New York who’s been frenziedly drawing his constant visions of Roland, the Tower, and a mysterious Man in Black who wants to destroy it. Jake is convinced, correctly, that otherworldly beings wearing human faces are working for the Man in Black, kidnapping children from Jake’s world and using them to essentially direct psychic laser beams at the Tower. When they inevitably come for Jake, he uses the knowledge his visions have granted him to elude capture and escape through a multi-dimensional portal to Roland’s world, a vast barren wasteland.

The main elements and characters who help Roland along his journey in the book series have all been merged into Jake’s character, effectively turning Roland’s story into Jake’s story — perhaps because at heart all Stephen King stories are about boys learning to be men. Here, it is Jake who must find Roland, learn about the Tower, and ultimately stop the Man in Black from blowing it up. If that happens, Roland assures Jake, the darkness the Tower currently holds at bay — an implied nebula of strange Lovecraftian cosmic terrors — will encroach upon all of their separate worlds.

Jake teams up with a reluctant Roland to travel from the desolate outposts of Roland’s world back into the bustle of New York, where they hope to find a portal to the Man in Black’s lair in order to destroy it before it can destroy the Tower. Along the way, they battle a strange attic-destroying demon, more Lovecraftian monsters, attacks from the Man in Black’s henchman, and Roland’s own warring sense of purpose: does he want mere revenge against the Man in Black for past wrongs, or does he want to save the world?

As Jake, Tom Taylor is clear-eyed and defiant, a fine foil for Idris Elba’s world-weary gunslinger. Although the movie is never quite sure what it wants to do with Jake’s powers, and seems to have no idea whether he’s a future gunslinger or not, Taylor pulls off a small miracle, in that he doesn’t make you resent that he’s the main character of this show instead of Roland. Taylor owns his role with an endearing, wary confidence. The rapidly forming bond between Jake and Roland — one of the most crucial elements of the Dark Tower series — and Jake’s power both become believable in Taylor’s hands. If mistrustful surly teenage glares are evidence of psychic abilities, Jake could probably take over the world.

2) Idris Elba finally gets a major role in a potential blockbuster, and he’s perfect

When the role of Roland went to Idris Elba, incensed Stephen King fans complained because King’s long been on record as envisioning the Gunslinger, the last remaining member of an order of soldiers who defend Roland’s world from darkness, as a Clint Eastwood type — in other words, white. Elba proves those fans and their outrage wrong before he ever says a word. Strong and silent, his Roland is an exhausted, heartbroken loner who slowly comes alive and learns to hope again over the course of the film thanks to his encounter with Jake.

We may not see the events that have taken place over the course of the Dark Tower series in this film, but Elba’s Roland has internalized them all the same. Whenever he aims a weapon, you fully believe that he kills not with his gun but with his heart — part of the Gunslinger creed. Elba is the physical embodiment of Roland, and he’s so committed to his vague, barely explained quest that he stays the film’s most deeply compelling figure, even if he’s no longer the main protagonist. When we finally see Roland attempting to interact with random people in modern-day New York, and see how out of place he is, the comedic moments are tinged with sadness: here is a man out of time who’s truly lost everything, won’t regain it, and knows it.

Without Idris Elba, Dark Tower could easily collapse under the weight of its own nonsense. Instead, he serves as its linchpin — something the unwieldy film desperately needs. As the Man in Black, Matthew McConaughey seems alternately bored and confused by his own motivations in The Dark Tower. He mainly seems to be doing all of this — kidnapping children and forcing them to shoot psychic laser beams at a multi-dimensional fortress — in order to annoy his old friend Roland. (Their history and former relationship are never fully explained.) He also seems to be aware, as Roland isn’t, that they have done all of this many times before, giving their dynamic an uneasy imbalance.

3) The film alternates between nonsensical plot ideas and genuinely scary, fun moments that make it a true Stephen King romp

But while McConaughey’s Man in Black isn’t truly menacing so much as oozing snake oil, the glimpses we get of the monsters the Tower is keeping at bay are creepy and fun. The film’s special effects are top-notch, and a reminder that King’s entire multiverse hinges on a Weird fiction view of the horrors out there in the cosmos. That the film features a nebula of creepy monsters from the beyond may make it feel like a Stranger Things ripoff to some viewers, but don’t be misled: Arcel is in fact honoring King’s longstanding Lovecraftian tradition.

Arcel also does his best to run with the interconnectivity of King’s universe, something that links many of his books but has really never made its way into a screen adaptation until now. The Dark Tower universe essentially ties all of King’s universes together; characters from the Dark Tower appear in other books, and characters throughout his fiction move between the worlds held in place by the Tower. On film, save for one element, these multiple worlds feel superimposed: a long-ruined theme park dedicated to “Pennywise” in Roland’s world implies that It’s shapeshifting titular character once ran the joint; a portal dubbed 1408 implies that the demonic hotel room of King’s 1408 is but a jaunt away; other subtler references to Salem’s Lot, Needful Things, and The Shining occur throughout the film.

Only one element we’ve seen before in a Stephen King film makes a dent on the plot: the Shining itself. Fans of Stephen King, or of the Kubrick film, may recall that the “shine” is a rare psychic ability to read minds and sense the future. Throughout Dark Tower, Jake is informed that he “shines,” that he has “the shine,” and that this is a rare gift — so rare we’ve seen it only in a few King characters here and there over the decades. This, too, might feel superimposed on the film, but it’s a loving reflection of the ongoing interconnectedness of King’s worlds — a crucial aspect of the Dark Tower series.

4) Where Dark Tower fails, it fails in exposition. But honestly, who cares?

From the first scene, when we see a group of children being creepily herded to their psychic laser beam-launchers with absolutely no context, The Dark Tower has a rushed, middle-of-the-battle feel that it never fully loses.

But that’s not really a bad thing. In fact, that’s partly what makes the film so much fun. It foregoes lengthy exposition and backstories, and while that makes for a disjointed narrative structure, it allows for a fast-paced story told mainly through scares and monsters and plenty of gunfights and Idris Elba asking Jake if the animals in his world still speak. (It also gets an assist from a tonally perfect score from Tom Holkenborg.) There’s a basic, wondrous glee in The Dark Tower that makes it feel more like a Stephen King film than any other Stephen King film since Stand By Me.

There are probably plenty of reasons to hate The Dark Tower if you go in looking for them. But if you go in expecting a fun fantasy with heart and a few scares, you may find plenty to love as well.

After all: We do not watch Stephen King movies with our brains. We watch Stephen King movies with our hearts.