I was a bit underwhelmed by Alex Garland's well-reviewed directorial debut Ex Machina. I thought it had good ideas but a draggy execution. There's more of the same in his followup, an adaptation of Jeff VanderMeer's novel, but Annihilation rises to a disturbing, hallucinatory finale that makes the film harder to shake.

Natalie Portman plays a biologist who, of course, also happens to be an ex-soldier. When her beloved Army husband (Oscar Isaac) suddenly returns, dazed and amnesic, after vanishing twelve months earlier on a black ops mission, she has understandable concerns. But before you know it, she and hubby are snatched up by government authorities and taken to a secret base.

Turns out Isaac's character was the only person ever to return from something called the Shimmer, an iridescent phenomena that has spread out over a National Park after a meteorite crashed into a lighthouse. For no reason beyond "I want to see this for myself", Portman joins a quartet of female soldier/scientists led by Jennifer Jason Leigh as they head into the Shimmer, only to discover a landscape rife with disturbing mutations.

For a while, we're in familiar sci fi/horror territory, with a team of brave but foolhardy souls facing a mysterious entity that starts picking them off one by one. This ground has been covered in everything from Aliens to The Thing to Predator to The Blair Witch Project. What sets Annihilation apart is its defiantly trippy third act, which I dare not reveal here. Suffice to say that, although the film creeps along at a glacial pace, with only a couple jump scares and gory moments breaking up the ponderous dialogue and somnambulistic forest trekking, stick with it – although the nearly dialogue-free finale will either mesmerize you or fatigue you.