(2015) **** 1/2
That's the best way I can describe this movie. There's very little I can say about the plot without giving any spoilers. The details that you don't necessarily want to know begin about five minutes in, and slowly unravel from there.
This film was very uncomfortable to watch. I squirmed numerous times, and hoped that it would end sooner than later. That isn't to say it's not a great film, on the contrary, it's amazing. It takes similar themes from The Babadook, and runs away with them. The acting is intense and jarring, the visuals are impressive, and the horror, as stated above, is horrific. It loses a half-star because some of the twists are obvious to anyone who has ever seen a horror movie before, but that doesn't make their execution any less skillful.
See it, see it, see it.