Louis Theroux presents the first of two films looking at the issue of law and disorder in two volatile and crime-ridden cities - Philadelphia and Johannesburg. In tonight's show, Louis joins the Philadelphia Police Department to experience front line policing American-style. In the most dangerous areas of the city, there are approaching 400 homicides a year and drug dealers on every corner. It is also considered part of normal life to carry a gun. Embedded within the Philly rapid-response teams, Louis feels a palpable sense of adrenalin mixed with frustration as police take on gangs and dealers night after night. He sees a world in which battle-hardened officers cruise the streets on constant gun alert, chase down dealers and patrol a community they feel they can never afford to trust. Day in, day out, this life inevitably takes its toll on officers who, just like those they are policing, find it very difficult to ever feel truly comfortable in the city they are supposed to make safe.