The new series focused on activity along the border between U.S. and Mexico, of people attempting to cross illegally into the United States and/or smuggle drugs and other contraband via the inhospitable Sonoran Desert in Arizona, where two boarder towns, Nogales, AZ and Nogales, Mexico, are separated by a security fence. National Geographic was given access to follow officers and agents of U.S. Customs and Border Protection (CBP) as they go about their duties in fighting terrorism and intercepting illegal entry into the U.S. by air and on the ground, using a variety of methods, including high-tech stealth planes.