Natalie Portman in Annihilation.

Annihilation, director Alex Garland’s film starring Natalie Portman, bills itself as a science-fiction/fantasy flick.

It is indeed sci-fi/fantasy—but on top of that, it is one of the scariest movies you will see this year. It’s also a legitimate horror film.

This alien-invasion movie, loosely based on Jeff VanderMeer’s novel, explores themes of self-identity and love (as did Garland’s 2014 debut Ex Machina) while mixing in environmental terror involving nightmarish creatures and transforming landscapes. It also features a startlingly brutal take on the ravages of infidelity. And did I mention it’s freaking scary?

There’s a lot going on in this movie—yet Garland and company balance it all out to make it a stunning piece of brainy entertainment.

In an opening sequence reminiscent of John Carpenter’s The Thing, an object enters Earth’s atmosphere and crashes to the planet. The zone surrounding the crash site becomes something known as The Shimmer, an environmental phenomenon featuring a visually swirling, bendy, translucent barrier no one can figure out. Numerous expeditions into The Shimmer have resulted in the loss of many people—but one man, Kane (Oscar Isaac), does return a year after his disappearance.

Kane is the husband of Army biologist-turned-professor Lena (Portman), and he doesn’t seem all there when he sits down at the kitchen table shortly after his mysterious return. He starts convulsing and spitting up blood, which prompts a trip to the hospital. Agent types overtake the ambulance, and Lena wakes up in a strange facility next to The Shimmer, in the care of Dr. Ventress (Jennifer Jason Leigh).

Before long, Lena is following Ventress into The Shimmer, accompanied by Anya (Gina Rodriguez), Cass (Tuva Novotny) and Josie (the increasingly amazing Tessa Thompson). Carrying guns and rations, their mission is to reach a lighthouse near the Shimmer’s origin; collect data along the way; and, unlike most who have preceded them, return with their observations.

Fat chance: It’s crazy in The Shimmer, unkind in so many ways to those who enter. Among its horrors: terrifying videos left behind by former explorers; messed-up wildlife, including mutated bears and alligators; and a general tendency to make those inside it batshit crazy. There are at least three scenes in this movie that made me want to die rather than watch them, because they were so damned scary; I was uncomfortable during a good chunk of the running time. That’s high praise for a horror movie.

To go with the dread, Garland adds a layer of sci-fi and mixes in some scary elements involving the Lena-Kane marriage. The results are a movie that goes to great lengths to challenge your mind—as much as it freaks you out.

Portman is great—Isn’t she always?—as a person determined to find out the root cause of her husband’s illness, so much so that she will endure psychological and physical fuckery. As her cohorts, Rodriguez, Novotny and Thompson all have shining moments, while Leigh provides a nice anchor. While he doesn’t have much screen time, Isaac (who also starred in Ex Machina) makes the most of his moments.

While he’s only two movies into his directorial career, Garland is proving he’s capable of many things. He’s a first-rate sci-fi auteur; he’s no slouch with pure drama; he captures stellar performances. And, without a doubt, he possesses some major horror chops. You think I’m exaggerating, but there are moments in this movie that will make even the most die-hard horror fans cringe and squirm. I would love to see him do a ghost story or pure monster movie.

Annihilation owes a lot to Ridley Scott (Alien), John Carpenter (The Thing) and any incarnation of Invasion of the Body Snatchers—yet it also feels very original. It’s 2018’s first masterpiece, a rare film that is a shining example within many genres.

Annihilation is playing at theaters across the valley.