Jessica Comley is an American border patrol agent posted in Tucson, Arizona, between the United States and Mexico. In this merciless desert, she leads with determination her mission to protect her country against drug trafficking and illegal immigration. One day, she commits an act from which there is no going back, in front of an old man and his grandson, both of them part of a Native American community. While her colleague attempts to make the crime look like an accident, Jessica has to face these inconvenient witnesses: it’s their word against hers.