"Un été d'enfer" is a French film that tells the story of a group of friends who decide to spend their summer vacation in a remote cabin in the mountains. As they settle in, they begin to experience strange and terrifying events that make them question their sanity. As the days go by, the friends realize that they are not alone in the cabin and that they are being haunted by a malevolent presence. They must band together and confront their fears in order to survive the summer from hell.