In the 1920s, the richest people per capita in the world were members of the Osage Nation in Oklahoma, thanks to the oil that was discovered beneath their land. Then, one by one, the Osage began to die under mysterious circumstances, and anyone who tried to investigate met the same end. As the death toll surpassed more than twenty-four Osage, the newly created Bureau of Investigation, which became the FBI, took up the case, one of the organization's first major homicide investigations. An undercover team, including one of the only Native American agents in the bureau, infiltrated the region, struggling to adopt the latest modern techniques of detection. Working with the Osage, they began to expose one of the most chilling conspiracies in American history.