Brothers Alex and David Pastor direct this Spanish horror centering around the life of project manager Marc (Quim Gutiérrez). After news breaks revealing that noxious gases are slowly consuming the earth, Marc and his colleagues become trapped in their office; they quickly run out of food and supplies and start to fear the outside world. Three months pass and Marc decides he needs to find his girlfriend, Julia (Marta Etura), and so with the help of his boss Enrique (José Coronado) Marc attempts to search Barcelona until he finds her. What will await him when he opens the door?