The demon kid subgenre, though old, can offer fresh chills, and edge of the seat excitement if offered in the correct platter. I think, Case 39 did the same and it was indeed an engulfed experience watching this despite the earlier negative reviews. Someone said about Orphan (by Jaume Collet Serra) starring Vera Farmiga falling into the same sub-genre, but it's not. There the disturbed child is actually suffering from an acute physical state that stops her from growing and which adds to her mental health owing to some disturbed past. Case 39 on the other hand portrays Lillith having been born with a demon soul that drives her into sinister deeds and that negative energy feeds on other people through the little girl herself. It's worth a watch. And, some creepy sequences are sure to leave that horror/thriller mark in the correct justification.