Moises (Gael García Bernal) and other undocumented people cross on foot a narrow border road between Mexico and the United States. They look for new opportunities and reunite with their loved ones. Unfortunately, the group is spotted by Sam (Jeffrey Dean Morgan), a demented “vigilante” who enjoys eliminating the immigrants. In the midst of the great difficulties of the desert, Sam relentlessly pursues Moses. It is a battle in which only the strongest will survive.