After an exchange student with bubonic plague turns up in a Reno hospital, a contractor with identical symptoms dies in Los Angeles. The government's official stance is that the cases are isolated and the outbreak is under control. But George Mack, a 30-year public health veteran, quickly realizes this is no ordinary plague. The death toll is too high, and the spread pattern make no sense. As Reno's hospitals fill with plague victims, Mack begins to believe that there is more to the epidemic than the CDC is letting on - and that he must take drastic steps if he hopes to save his city. Medical resident Dr. Susan Barry just wants to finish her training and get a real job. But when plague patients start showing up in her Los Angeles hospital, her plans for the future suddenly go off the rails. Faced with a growing crisis, Susan teams up with an old research mentor to determine the unthinkable: Is the rapidly spreading plague an act of bioterrorism? Racing against the clock, Susan must also confront another disturbing possibility. She may be one of the plague's few survivors. In eastern Oregon, John Harr makes a pact with his fellow ranchers to keep the "California" plague out of the high desert where they live. Using roadblocks and quarantine, Harr and his neighbors think they've secured their home - until a mysterious and heavily armed convoy comes to town, and Harr must use training from his past life in the military to protect the people he loves.