Nate Foster is a young, idealistic intelligence analyst for the FBI. Highly educated, and fluent in Arabic after serving in Iraq with the State Department, he's joined the Bureau to protect the country from another 9/11. But he's beginning to realize that the 'Islamic terrorist plots' he's busting are often setups - overzealous attempts to reassure an anxious public, and meet the latest quotas.
So when the FBI discovers a smuggled shipment of Cesium-137 - the primary ingredient needed to build a dirty bomb- Nate is willing to hear out Angela Zampino, a case agent who's convinced the plot is the work of white supremacists. She explains their overwhelming history of violence, going back to Oklahoma City, and their obsession with obtaining weapons of mass destruction.
But the hardest sell of all is convincing Nate to do the unthinkable - to leave his office job behind, and use his superior intelligence and people skills to go undercover, and infiltrate the community.