I found this movie in a list of top thriller movies. Though it is engaging and watchable once, there are too many unanswered questions at the end. Many plotholes which do not give proper closure. Maybe if they were answered, this film might have been a good thriller movie.
Spoilers ahead:
Why did David visit the pestersons? Why did he kill them for no reason? First it seems like he was doing good to the family but all of a sudden he is on a killing spree once the cops reach his place. A backstory might have helped