This was a movie that I watched this year (2014) and I believe that it was recently made.
The movie starts off in a Movie theater where the man is welcomed by a ticket taker who I believe is supposed to be a representation of the devil (the theater is in theory their personal hell as the man comes back to it at the end of the film.)
It is about this man who goes into the woods with his wife, best friend, and a girl he met at the theater as well as some other people trying to solve a mystery of a town of people that just picked up and left going through this Pass and were never seen again.
They are walking around the woods and their equipment starts to go faulty. There is loud music blaring from an unknown source, and essentially they all go crazy. The wife is cheating with his best friend, one person steals a bag of candy, two people fight over a hat and one ends up being murdered.. chaos ensues until everyone but the man is dead.
He finds his way back to town and into the movie theater again.
Please help me remember what this movie is!