Overview: This episode examines the effects of a hypothetical radiological attack from a car bomb on a major U.S. city. The purpose is to give useful information in the event that such an event should occur. The stories of several characters are told to dramatize the effects on various types of people: those responding in the "hot zone", a person near to the blast whose symptoms develop over time, a pregnant woman who must evacuate, and investigators who comb through debris to determine who set the blast.