Killers of the Flower Moon is a 2017 nonfiction book by David Grann that tells the story of the Osage “Reign of Terror” in the 1920s (and beyond), in which numerous Osage tribe members were killed in Oklahoma for their oil wealth. The book details these killings and the investigation into who was responsible. The Osage, like many Native American tribes, had been pushed west by white settlers, until finally settling in a rocky area of land in what would become the state of Oklahoma. They hoped that the poor soil, unfit for farming, would keep white settlers from dislodging them yet again. When oil was discovered in Osage territory, however, the tribe became quite wealthy. They owned what were called “headrights” to the oil; these headrights could not be bought or sold, only inherited. As a result, nefarious whites and con men devised ways to steal the tribe’s money. One of these ways was murder.

The book is organized into three sections, with the first introducing the killing spree through the family of Mollie Burkhart, whose mother and three sisters were all killed. Grann details the death of Mollie’s sister, Anna, as an example of the kinds of mysterious circumstances that accompanied most of the Osage murders. Victims were shot, poisoned, and involved in car accidents, and investigations by the authorities and private agencies seemed to lead nowhere. Several people, including whites, who investigated the deaths or sought help from the federal government also turned up dead. The killer or killers, meanwhile, went free. Both Mollie and Anna were married to the Burkhart brothers, white men whose uncle, William Hale, was among the most prominent and influential citizens in the community. Hale pledged to use his resources and connections to help find Anna’s killer.

The second section of the book focuses on the investigation of the murders by the Bureau of Investigation (the precursor of the FBI). Heading the investigation was Tom White, an old-style lawman from Texas. Together with his team of agents, he uncovered shocking evidence that Hale and the two Burkhart brothers were behind many of the murders. Hale, Ernest Burkhart (Mollie’s husband), and an accomplice were tried and convicted in court. The case helped to bolster the reputation of the Bureau after a series of scandals in the early 1920s, and Grann ends the section with a review of the simultaneous rise of the Bureau and its head, J. Edgar Hoover, in the mid-20th century. Grann also outlines Tom White’s later career as prison warden, as well as his retirement years.

In the final section, Grann writes about his research trips to Oklahoma and Texas, in which he seeks answers to lingering questions in the case. He talks to several descendants of victims, including Mollie Burkhart’s granddaughter, Margie Burkhart. What he learns is that the Osage Reign of Terror actually lasted for a longer period of time than the official record showed. The Bureau’s investigation had focused on Hale as the mastermind behind the killings, but many deaths were not classified as murders and many victims were targeted but not killed. Evidence of murdered Osage in the 1910s and 1930s indicate that the terror was more widespread than thought, as Hale was incarcerated in the 1930s and couldn’t have been part of that period of killings. Grann concludes that the killings involved and encompassed virtually the entire community in Osage County.