"Shelley" won't work for everyone. It's certainly haunting enough, set firmly in the pregnancy subset of the horror genre, but it chooses atmosphere over scares and that might not be what you're looking for when you pop in a horror flick. Buyer beware.
The debut feature from director Ali Abbasi certainly delivers on atmosphere, and the performances from the leads (Ellen Dorrit Petersen and Cosmina Stratan) bring home the goods. A Romanian maid (Elana) comes to live with a Danish couple as the wife (Louise) recovers from surgery after a failed pregnancy. Then Things Go Horribly Wrong. Sort of.
This isn't the type of film where things go bump in the night and an evil presence begins to creep into the house from day one. Elana agrees to carry Louise and Leo's child because she needs the money. The subtext of the film is very much the pain and haunt of an unwanted pregnancy and boy howdy does this shit get ugly.
"Shelley" doesn't quite get to "The Babadook" levels of "hey, being a parent seems pretty terrible," but it plays into similar anxieties. Elana experiences nightmares, feels attacked by her unborn child and is otherwise under siege psychologically because of her pregnancy with no relief. The tension is fabulous but I'm sorry to say the payoff at the end of the film doesn't deliver the goods.
This is a little different than criticism I've had for other horror films, though. I don't think "Shelley" ever intended to do more than this. "Shelley" always wanted to be an atmospheric film about the psychological cost of an unwanted pregnancy and it nailed it. That's fine, but it only succeeded at making half a movie.
There's something to be said for a horror film that breaks convention, but that doesn't mean making a movie where nothing happens. It's a fine line, I realize, but I feel "Shelley" too often sits on the wrong side. It's a fine movie, but with a little more payoff it could've been a better one. As long as you know what you're getting yourself into, I think you'll dig it.