After rising through the ranks of her male-dominated profession, idealistic FBI agent Kate Macer (Emily Blunt) receives a top assignment. Recruited by mysterious government official Matt Graver (Josh Brolin), Kate joins a task force for the escalating war against drugs. Led by the intense and shadowy Alejandro (Benicio Del Toro), the team travels back and forth across the U.S.-Mexican border, using one cartel boss (Bernardo Saracino) to flush out a bigger one (Julio Cesar Cedillo).