The new film from Alex Garland (Ex Machina) is adapted from the novel of the same name by Jeff  VanderMeer, but its roots go deeper than that. Aficionados of sci-fi horror, of which this is a sterling example, will doubtless recognise the influence of John Carpenter’s The Thing on this story of a group of scientists who have to contend with the alien and dangerously uncanny, but really Annihilation smacks of horror grandmaster HP Lovecraft’s short story The Colour Out of Space, first published in 1927, which tells of a wilderness area affected by a strange meteor that causes strange mutations in the local plant and animal life.

Here the area is a vast stretch of Floridian swampland, the effect is called “the shimmer” for the pearlescent quality of the atmospheric barrier that separates the afflicted zone from the rest of the world, and Lena (Natalie Portman), a cancer specialist and army veteran, is one of a group of five women (the others are Jennifer Jason Leigh, Gina Rodriguez, Tuva Nuvolny, and Tessa Thompson) sent in to try and learn anything about the weird goings-on. They’re not the first team of investigators sent in, and they know it’s probably a suicide mission. Each has their own motive for volunteering.

Lena’s is guilt; her affair with a colleague prompted her husband, Kane (Oscar Isaac) to volunteer for a prior expedition, and he is the only explorer to return thus far, terribly ill, emotionally numb and on the brink of death. The need to find out what has happened to him drives her on, even as she and her team are confronted with missing time, mutated predators (the shark-toothed alligator seen in the trailers is not the worst), and mounting evidence that whatever is changing the local wildlife is also changing them.

Garland, who also wrote the script cannot directly translate VanderMeer’s famously oblique and elliptical novel directly to the screen, but he does take it as the basis for a remarkably effective horror movie that practically drips eerie atmosphere as thick as the swampy humidity of its setting. And it is, beyond doubt, a horror movie, complete with grotesque creatures and some unusually high-end gore, including one scene of evisceration that is particularly hard to forget.

However, like all the best horror, Annihilation is steeped in character, mood, and ideas. The acting across the board is top notch, with each of the women in the squad granted distinct personalities and tics in a scenario that pretty much defines them by their jobs (indeed, the source book doesn’t even give them names). For all that the blood and the monsters are effective, it’s the film’s foreboding, relentless tone that lingers in the mind – the sense of the alien intruding into and poisoning the mundane world. Ravening alligators are one thing, but it’s the way Garland shows the natural landscape changing that really disturbs: in one scene we see deer with floral antlers; in another, shrubs that have taken on the semblance of human form.

Our characters are changing, too, including our nominal point of identification, Lena, and Annihilation pulls some clever tricks messing with our understanding of what we are seeing. The whole thing is told in flashback, as Lena is questioned by a bio-hazard-suited interrogator (Benedict Wong), and canny film-goers know this is shorthand for “unreliable narrator”, but the film goes further than that. As things get weirder and more dangerous as the expedition heads deeper into the shimmer, a semi-plausible rationale for what’s happening is foregrounded, but little supporting evidence is offered, suggesting rather tantalisingly that while the characters can make inferences about the phenomena they’re witnessing, they’re simply filtering what they’re experiencing through their own preconceptions; any semblance of concrete truth or verifiable fact drifts further out of reach as their own subjectivity is stressed by the shimmer. As each character’s understanding of what is or might be happening veers further away from the others’, paranoia begins to take hold and, inevitably, violence. It’s incredibly unsettling, and perhaps the first time an onscreen alien encounter has felt actually alien since, well, Alien (or, you know, The Thing).

It’s hard to say right now if Annihilation is worthy of being set alongside those worthy films at so close a remove but if it doesn’t, it comes oh-so-very close. At the very least it’s a rock solid, strikingly effective sci-fi horror movie constructed with rare skill and absolute commitment to its own guiding ethos, and that’s nothing to sneeze at.