Soon after 9/11, an FBI informant made an alarming claim: Osama bin Laden's deputy, Ayman al-Zawahiri, had visited the town of Lodi, Calif. in the late 1990s and attended a mosque there. Moreover, two Pakistani imams preaching at the mosque came from a conservative Islamic school, or madrassa, linked to the former Taliban regime in Afghanistan. According to McGregor Scott, the U.S. attorney who led the federal anti-terror investigation, this was "an attempt by a group of radical Islamic religious figures to come to this country and … establish a madrassa to serve as a recruiting ground." However, a deeper look at the evidence creates uncertainty about what kind of threat actually did exist in Lodi and provides a case study of America's response to the threat of domestic terrorism. In "The Enemy Within, " FRONTLINE and New York Times reporter Lowell Bergman examines the Lodi case and interviews FBI and Homeland Security officials to assess U.S. anti-terror efforts