The Visit - A plot twist

I recently saw the movie The Visit which to be honest I have been wanting but dreading to watch for quite some time now.  The reason for this is because I am not a huge fan of horror films but I do enjoy them on occasion.  The Visit is played by Olivia DeJonge as Becca and Ed Oxenbould as Tyler, which are the grand kids.  The grandparents are played by Deanna Dunagan and Peter McRobbie as Nana and Pop Pop.  The plot of the movie was interesting to me because I always loved staying the night at my grandparents on the weekends.  The Visit begins to explain how the siblings mother ran away from her parents at the age of 19 years old and never spoke or contacted them again.  But now that the kids are a bit older and curious who raised their mother, they plan on a visit to their grandparents for a whole week.  Their mother lets them do this and sends them off by train to go meet their grandparents.  Everything seems well at first with the meeting of the grandparents but then evening comes and they begin to see weird behavior from the grandparents.  Towards the end of the film is when the twist comes in that grabbed my attention in how well the film was made.  It ended up that the mother had never saw who her kids were actually staying with until they showed here by a Skype call.  This is what made my heart skip a beat and not the actual scary parts of the movie as much.  We come to find out that the old couple they have been staying with killed the kid's actual grandparents and just wanted a "fun" week for his wife, Nana.  Eventually the kids escape the house safely and all is well.  This horror film to me was one of my favorites that I have ever seen and had a great plot turn to it that kept you on the edge of your seat.