Alexandre Aja’s Crawl is more than a movie about a young woman trapped in a crawlspace with a giant alligator in the middle of a hurricane, it’s a shriek of glorious existential despair. So much goes wrong for the protagonist over the course of this seemingly simplistic horror movie that it elevates the film above its genre origins and transforms it into a kind of breathtaking, cosmic joke.

Murphy’s Law wasn’t specifically written with man-eating reptiles in mind, but after watching Crawl I can’t help but wonder if maybe it should have been.

Crawl stars Kaya Scodelario (Extremely Wicked, Shockingly Evil and Vile) as Haley, a college student and competitive swimmer whose father has gone missing at the start of a Category 5 hurricane. Haley drives into the thick of the storm, only to find her father Dave (Barry Pepper, Maze Runner: The Death Cure) incapacitated in the crawlspace under his house with a gigantic bite mark on his shoulder.

As Haley tries to drag her father to safety, and as the winds pick up outside and the water levels rise around them, she’s attacked by an exceptionally large alligator, which completely blocks their escape. It takes all the effort and creativity they can muster to figure out a way around the beast, but as soon as they do they discover an even bigger problem… and I wouldn’t want to spoil it.

Even so, it’s a premise so unbelievably thin it’s almost hard to imagine there would be enough material for a whole movie, but Aja – working from a deft script by Michael & Shawn Rasmussen (The Inhabitants) – finds an enormous number of ways to make Crawl more complicated at every turn. There’s nothing that happens over the course of this movie that goes just right, and every time Haley and Dave are able to change positions, signal for help, or reach their cell phones something completely unexpected and awful happens, and makes their already impossible situation more life-threatening and difficult.

Crawl evokes the same exhilarating sense of hopelessness that the best Sam Raimi movies do, so it makes sense that he’s also the film’s producer. The same maddening suspense that built and built until it finally drove Ash Williams insane in The Evil Dead 2 can be sensed in Aja’s latest film. Crawl is not as shockingly violent but it has the same twisted sense of humor, as though the filmmakers were giggling like maniacs every time they came up with a new way to ruin Haley and Dave’s plans.

Of course, to make room for that raw, nervous laughter intensity, the filmmakers also stripped the narrative fat off of Crawl until, frankly, there wasn’t much left. Haley and Dave’s personal baggage is incredibly flimsy and easy to resolve, but if this film was full of subplots and nuances then the sucker punch sensationalism probably wouldn’t have come across. It’s an interesting example of a seemingly obvious storytelling “flaw” that actually improves the entire experience.

Barry Pepper gives a fine and noble performance as a failed husband and father who, frankly, doesn’t even feel like he’s worth saving. But this is Kaya Scodelario’s film, and she captures the audience’s attention and never lets go. She’s a naturally magnetic performer, and once you’re drawn into her charismatic and believable performance she musters subtlety and determination from unexpected depths. On paper, her character seems simplistic, but Scodelario turns Haley into an inspirational horror hero.

Haley is fantastic because she’s not only fighting the elements, and not only fighting man-eating beasts, but because she’s fighting against an entire world that actively wants to destroy her. And who hasn’t felt like that sometimes? Watching Crawl is like watching someone fight back against the personification of death in the Final Destination movies. The odds are spectacularly against them and yet, somehow, – through her strength of conviction if nothing else, we think Haley might actually have a chance.

Crawl is not just a fantastic, crowd-pleasing, popcorn-spilling scary movie. If you look at it the right way it’s genuinely inspiring. But in the end, whatever meaning you’re able to wrench from it, Crawl is undeniably also just a killer alligator movie with very modest ambitions. It only seems to aspire to be a three-star movie, but it’s about as good as a three-star movie can possibly get. It’s a “Four-Star Three-Star Movie,” and it’s one of the most unexpected and satisfying genre films of the year.