In the 1920s, the richest people per capita in the world were members of the Osage Indian nation in Oklahoma. After oil was discovered beneath their land, they rode in chauffeured automobiles, built mansions and sent their children to study in Europe. Then, one by one, the Osage began to be killed off. As the death toll climbed, the FBI took up the case ... Oil, money, murder and the birth of the FBI.