It was Swedish or Norwegian or Finish or something. A blonde lady was moving to a town with her son I think.. On the way she hits someone and drives off. When she eventually goes back later the body is gone. And theres a big black rock in the forest that all the towns people seem to worship and it has special powers or something? Then in the end it transpires that the person getting run over was part of a big plot to keep her in the town or something.
It was maybe 4/5 years ago and I really loved it and want to watch it again.
Any ideas?