The directors needed to provide more emotional clues to the father's reaction when his discovers the stash of female victims. Failure to so, left me concluding that the father was the perpetrator. Further, there are many instances in quite dramatic scenes where the editing is very sketchy as the mother ventures into quite dangerous situations without first arming herself. I found it quite incredulous that such an experienced person would not protect herself.
Overall the plot is intriguing though some rough edges thought through more carefully would have made the film more believable..