The film begins with Pat, Sam, Reece, and Tiger, members of a punk Band on the road when they meet a local radio host who gives them one more gig that his cousin knows of. This is their last event of their tour and they blindly go to a Neo-Nazi bar, deep the the Oregon forest. They play their music and are about to leave when Pat goes back into the green waiting room and discovers a girl thats been stabbed to death and her friend crying. He calls the poice and the band lock themselves into the room, while the staff of the bar try to break in and kill the band for witnessing the murder.
The movie came from Saulnier's desire to create a thriller set in a green room, calling the idea "an obsession" Saulnier created a short film set in one as part of a 48 hour film challenge in 2007 although that involved the supernatural and according to Saulnier "Really kind of fun and hammy." However he still wanted a chance to do his green room movie "the right way. Although the film features a large amount of violence and what Saulnier calls "full frontal gore" he has gone on record as stating that it is not "sadistic", and that every act of violence apart from the initiating incident is done with a reason. As such Saulnier's made sure that there were no "gratuitous close ups" of recently deceased characters.
On May 22, 2014, it was announced that Broad Green Pictures would finance and produce the crime thriller film directed and written by Jeremy Saulnier, with Film Science. Anish Savjani, Neil Kopp and Victor Moyers would produce the film. On October 16, Anton Yelchin and Imogen Poots joined the lead cast of the film, along with Alia Shawkat, Callum Turner, Joe Cole, Macon Blair and Mark Webber. On October 21, Patrick Stewart was added to the cast to play Darcy Banker, the leader of a violent white supremacist group, while other cast includes Kai Lennox, Eric Edelstein and Taylor Tunes.