Natalie Portman heads toward unknown dangers in the first full-length trailer for Annihilation, the sci-fi horror film from Ex Machina director Alex Garland.

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It's an adaptation of Jeff VanderMeer's 2014 novel, the first part of the author's Southern Reach Trilogy, which follows a biologist (Portman) whose husband returns, near death, from an expedition into Area X, a mysterious uninhabited region cut off from civilization for decades. Although drones and other expeditions have been sent into Area X, only to never return, Portman's character leads her own team into the region in hopes of finding a cure for her husband (Oscar Isaac). What they find there defies belief.

Here's the synopsis of VanderMeer's novel:

Area X has been cut off from the rest of the continent for decades. Nature has reclaimed the last vestiges of human civilization. The first expedition returned with reports of a pristine, Edenic landscape; the second expedition ended in mass suicide; the third expedition in a hail of gunfire as its members turned on one another. The members of the eleventh expedition returned as shadows of their former selves, and within weeks, all had died of cancer. In Annihilation, the first volume of Jeff VanderMeer’s Southern Reach trilogy, we join the twelfth expedition.

The group is made up of four women: an anthropologist; a surveyor; a psychologist, the de facto leader; and our narrator, a biologist. Their mission is to map the terrain, record all observations of their surroundings and of one another, and, above all, avoid being contaminated by Area X itself.

They arrive expecting the unexpected, and Area X delivers—they discover a massive topographic anomaly and life forms that surpass understanding—but it’s the surprises that came across the border with them and the secrets the expedition members are keeping from one another that change everything.

Written and directed by Garland, Annihilation also stars Jennifer Jason Leigh, Gina Rodriguez, Tessa Thompson and Tuva Novotny. The film opens Feb. 23, 2018.