Jeff VanderMeer’s novel Annihilation is, as the New Yorker describes, a paradigm of “weird fiction.” The first volume of his Southern Reach trilogy, all published in 2014, the book doesn’t develop along the lines you’d expect, and its surrealistic imagery develops into an elaborate, unresolved meta-allegorical conceit.

That doesn’t sound like the stuff of a page-turner, but VanderMeer’s developed a wide readership in part because of his skill at drawing you in. Annihilation has a setup instantly familiar to fans of speculative fiction: a mysterious Area X is growing upon the Earth, engulfing flora and fauna behind its shimmering wall. People go in, and when they come out they’re fragile, hollow shells of themselves. We follow another exploratory party inside — this time, they’re all women — and then, VanderMeer’s got us.

Alex Garland’s new film adaptation cops that basic premise, a few main characters, and the notion that the story will culminate in a mysterious encounter. Beyond that, most bets are off. A controversy over whitewashing has critiqued the casting of Natalie Portman in the leading role — noting, as revealed in the trilogy’s second volume, that her character is of Asian descent.

The casting is “really unfortunate,” in Portman’s own words, but the film also reveals why neither the writer-director nor star apparently felt the need to read as far as the sequel. (Neither did I, but only because I found the climactic metaphor dump so annoying.) The title of Annihilation refers not only to the fate Portman’s character fears, but to what Garland did with VanderMeer’s plot.

What emerges at the other end of this cinematic transformation isn’t as compelling as the more confined explorations of Garland’s superb Ex Machina (2015), but nonetheless a notable addition to the ranks of sci-fi mindfucks (2001, Solaris, Altered States). Once you stop trying to understand what’s going on, you’ll suddenly realize that it’s not that tough to figure out after all. Just eat your popcorn and watch the pretty colors.

There are lots of pretty colors in Annihilation, which turns on the notion that something within Area X is “refracting” the genetic makeup of living things that fall within its field. I’m pretty sure that would just straight-up kill you, but I’m willing to suspend my disbelief to see flowering vines that grow in the shape of humans; an alligator with shark-like rows of concentric teeth; and rainbow-hued rainforests. Entering Area X, in this film, is kind of like going on a color run with no possibility of a shower. Ever.

Portman would seem to have the ideal balance of tough and delicate for this assignment, but it’s hard not to speculate about what might have happened if Garland had cast the role with an actor without so familiar a steely resolve. (Even an Oscar-winner can’t do much with dialogue like: “That’s literally impossible!” “Well, that’s literally what’s happening.”)

Much has been made of the film’s diverse woman-led cast, which is certainly significant by action-movie standards, but the whitewashing debate isn’t just about fidelity to the book: that ship sailed as soon as Garland started tapping out his screenplay. It’s about the yawn the film elicits when we realize that Portman and her costar Jennifer Jason Leigh play the only developed characters. Even Oscar Isaac, seen largely in flashback as Portman’s husband, is just a cipher.

The movie does have one truly unforgettable scene, involving a carnivorous beast with an unusual roar. Garland remains best at close encounters, aided here by the enveloping sound design that becomes increasingly central to the film’s effect. The score, by Geoff Barrow and Ben Salisbury, wraps itself around the action like a python, ready to suddenly constrict.

“Helplessly Hoping,” as performed by Crosby, Stills & Nash, drifts through a couple of key scenes in Annihilation. The film put me in mind, though, of another song from that era — the one that goes, “freedom’s just another word for nothing left to lose.” What might this movie have become if Garland didn’t have quite so much to lose?

– Jay Gabler