The action begins with Mexico City policemen banging on the door of what seems to be an abandoned house. Ulises (Damian Alcazar) and his partner enter the house and find gruesome remnants of animal sacrifices and human remains. The two are ambushed by the occupants and Ulises is forced to watch them mutilate his partner. Ulises is allowed to live and told to warn other law enforcement officials to let sleeping dogs lie. The action shifts to Ed (Brian Presley), Henry (Jake Muxworthy) and Phil (Rider Strong), three recent Texas college grads, who are enjoying a college beach bonfire. They decide to head down to Mexico for the week to hit up the strip clubs and take advantage of a lack of law enforcement. Ed meets Valeria (Martha Higareda) and is immediately smitten while Henry sets Phil up for his first sexual encounter with a prostitute. The boys, Valeria and her cousin Lupe (Francesca Guillen) indulge in some magic mushrooms before going to a carnival, and the impending nightmare is nearly tangible. Sure enough, Phil encounters the man who mutilated Ulises' partner the year before. As he walks home from the carnival alone, Phil decides to get into a car with a couple of men who proceed to abduct him. When Phil does not come back, the boys begin to investigate, finding the local authorities uncooperative and the townspeople utterly terrified of Phil's captors.