Wow! My kind of horror flick in so many ways.
This is based on a novel and directed by David Bruckner, who did The Signal, back in 2007, a segment on 2012's V/H/S, and a pretty cool little flick called Southbound (also streaming on Netflix) back in 2015.
This is solid film making here, beautifully shot in Sweden, with strong performances and characters you can actually care about. For me, the monster design was also very powerful and unique.
It plays creepy for the first 45 minutes or so, then gets downright crazy in the finale, where the monster is finally revealed. This is highly recommended.
Grade - A