The film is adapted from David Grann's best-selling book "Killers of the Flower Moon: The Osage Murders and the Birth of the FBI", focusing on the "Osage Indian Murders" in Oklahoma, USA in the 1920s. At that time, the Osage people received continuous huge income from the discovery of oil mines in their native place. In order to prevent the above arrangement, someone planned serial murders, and 60 people were killed in 4 years, shocking the whole country. For this reason, the US government established the "Investigation Bureau" (the predecessor of the FBI) to conduct a cross-departmental investigation, revealing that the "Osage Guardian Program" that protected the rights of the Osage people was extremely corrupt; in the end, even with a lot of evidence, only a few murders were prosecuted.