It’s “day zero” of the initiation ritual at the Tolentino university residence. First-years Carlos and Dani willingly accept the challenge to prove themselves in the hope of fitting in and making friends. They are led into “The Catacombs” in the basement of the dormitory, where they are given the choice to leave immediately. Carlos and Dani choose to stay. Over the next 24 hours, they are subjected to an alcohol-fuelled rite of passage at the hands of their fellow students, commanded by cynical, elitist final-year student, Pepe. Carlos and Dani are forced to confront their own worst instincts before the violence escalates beyond control.