Shelley

For the past decade, screenwriters have been working hard to come up with new ways of isolating their protagonists - ways that work around the narrative challenges posed by mobile phones. In Shelley, Kasper (Peter Christoffersen) delivers the best one yet: simply, "We don't have electricity."

Kasper and Louise (Ellen Dorrit Petersen) "try to live a simple life" in their isolated woodland house on the shores of a Danish fjord. The light their house with oil lamps and grow most of their own food. But Louise, we are told, has health problems and is struggling to keep up with the work that needs to be done. That's why they've contracted young Romanian domestic worker Elena (Cosmina Stratan) to help. Elena has to make money somehow; she wants to buy an apartment so that her young son, who is currently being cared for by her parents, can have his own room. When Louise suggests that Elena become a surrogate mother and bear a child for her, in return for which she would give her all the money she needs after just nine months, it seems like the perfect arrangement. Naturally there are nerves. Both women know it's not something to be taken lightly. But things develop in a way Elena could never have anticipated.

Nadim Carlsen and Sturla Brandth Grøvlen's cinematography makes the most of natural light sources and, where necessary, imitates them well. The location helps, the air often saturated with water to create an indefinite glow. The night is pitch black unless we are close to a source of fire, which immediately creates a sense of something primal; by the time we see headlights at night we, like Elena, have grown so unused to the harshness of electric light that they seem harsh, almost threatening. By day the mossy slopes and reedy shore are overlooked by a blanched sky and director Ali Abbasi' camera makes much of the way that Peterson's ivory face blends into it, making her unusual beauty seem inhuman. She's framed against the sky and the water as if she is more a product of their intersection than of the civilisation from which she keeps her distance ("Something about her being allergic to electricity," Elena explains in a rare phone call to her mother). It's something that instills wariness in the viewer right from the start, even while Elena's gentle cynicism about her use of a mystical healer encourages us to dismiss such notions.

There's knowing irony in the role reversal we see here - the Eastern European with a humble background finding herself living a much more primitive lifestyle in the company of her comparatively wealthy Northern European employers; the dark eyes Romanian coming to suspect something supernatural about a grey-eyed Scandinavian blonde. Yet Shelley doesn't dwell on such notions, even if it overindulges in other ways. That idyllic natural world, whilst changing very little in prospect, comes to seem more and more threatening. What begins with intermittent cramps which Elena says she experienced during her first pregnancy gives way to constant pain, disturbing dreams and an increasing sense of dread. As Elena begins to wonder what it is that's growing inside her, there's a hint of something else out there among the trees. Who, or what, is Shelley?

Every horror film themed around pregnancy wants to be Rosemary's Baby, but this gets closer to succeeding, at least in atmospheric terms, than most. Narratively deceptive, it never quite fulfills its potential, but it has a rare, haunting quality that marks it out.