Nate Foster is an FBI agent working to uncover terrorist plots. After some illegally imported caesium-137 is stolen, Foster is recruited by agent Angela Zamparo to perform undercover work to track it down. Zamparo suspects the involvement of White supremacy groups over the suggestion of Islamic extremists after she hears a broadcast from incendiary Conservatism talk radio host Dallas Wolf hinting at an impending race war involving radiological weapons. Although Foster is bookish and introverted, Zamparo believes his ability to form genuine connections with hostile criminals makes him well-suited for the job.