A real chiller. It was slow-burn terrifying ... it will leave you wondering what could have been done and why the parents didn't communicate more. John C. Reilly's character wasn't developed nearly as much as the movie really only digs into the mother and son characters. An incredible performance by Tilda Swinton.
I have to say I completely disagree with the reviewer who blames the mom. The child was a sick manipulator from the start who was hateful beyond reason to her and played the father in order to draw a wedge between the parents.