Hector, a young Zapotec fleeing Mexico for a better life in the US with his friend Cesar, a biotech researcher, pays to be smuggled across the border by unscrupulous "coyotes," concealed in the tightly sealed, empty tank of a water truck packed with illegal migrants. Abandoned by the smugglers in the desert, they are left to die, their only lifeline Cesar's phone. As legends fuse with the terrifying present, the dangers Cesar is fleeing become grippingly apparent.