Scarlett Johansson plays an alien posing as a human to prey upon unwitting males.

The first half plays terrific. Johansson drives around an always dark Glasgow, asking for directions and luring men into her car. These scenes feel authentic (most men were unaware they were being filmed and later signed releases) and paint Johansson as an alien predator. She delivers a nuanced performance, flicking between icy detachment and warm flirtation. Her accent adds to the dissonance.

Once she hooks a victim, she takes them back to her out of the way cottage, where they’re entombed in a strange container. It’s a surreal sequence presented without explanation, but conveys a sense of something happening beyond human comprehension.

Later, we see what becomes of these trapped victims in a scene that delivers a jolting jump-scare that feels yanked from a Lovecraftian nightmare. It would be the most disturbing part of the film, except there’s a later scene involving Johansson’s handler, a baby, and a beach that pained me to watch. It’s just a man walking down a beach to collect something, yet it proves a masterpiece of cinematic storytelling.

At this point, I was hooked. Director Jonathan Glazer’s decision to tell the story from Johansson’s point-of-view tints everything with a hint of alien menace. Motivations elude us, but potential abounds. I was excited to see what frontiers Glazer would broach.

But then the film shifts. Johansson goes native and flees her handler. She takes up with a man and struggles with human emotions. No longer an apex predator, as the film concludes, she finds herself the prey.

I appreciated how Glazer sticks to constraints imposed by Johansson’s POV. How he shows rather than tells. Highlighting an amazing performance, the wordless scene where Johansson self-identifies while looking into a mirror proves a master class in restrained acting.

But I knew this story. Rather than chart alien territory, Glazer retreats to familiar turf. He tells this story well, resulting in a good movie. But given the first half’s potential, it could have been great and I couldn’t suppress a lingering sense of disappointment.