FRONTLINE returns to Iraq, this time to embed with Halliburton/KBR, and to take a hard look at private contractors who play a critical role in running U.S. military supply lines, providing armed protection and operating U.S. military bases. Their dramatic story illuminates the Pentagon's new reliance on corporate outsourcing and raises questions about where they fit in the chain of command and the price we are paying for their role in the war.