Racism
Racism is a major theme in Killers of the Flower Moon. The book describes a period in the 1920s when many Osage tribe members were brutally murdered in the state of Oklahoma. While there is still no full accounting of the scope of this tragedy, the book shows the prejudice at the heart of these crimes. In great detail, Grann describes the hate that runs rampant among the white people around the Osage reservation. The instances of this are numerous and range from the insults casually thrown at interracial couples to the violent jealousy directed towards people like Anna Brown and Henry Roan for their wealth. The book's central crime hinges on racism, as Hale and his henchman had to view the Osage as less than human in order to carry out their conspiracy. In the same way, the men who attempt to protect Hale during White's investigation and subsequent trial all share a clear dislike of and disrespect for the Osage. The prevalence of these crimes, as described in the book's final third, shows the clear intent of many wealthy white landowners to destroy the tribe and steal its money, with no hesitation or remorse.
Greed
Greed is another major theme in the book. Grann points out how white landowners quickly became envious of the great wealth that the Osage tribe had come into when they discovered oil on their land. This led to an escalating series of incidents. In the beginning, these individuals made various attempts to scam the Osage out of their money, by charging them exorbitant rates at local businesses or pursuing strategic marriages with them. However, as this greed continued to grow in intensity, violence ensued. White discovers that the murders in the tribe were the result of a conspiracy, run by Hale, against the Osage to systematically kill them off and steal their wealth and land rights. Grann then reveals that these crimes were even more widespread than previously thought, showing how the combination of financial envy and racial hatred ignited these horrible acts.
Justice
Justice is also a key theme in the book. Mollie seeks out justice for her murdered family members, as she refuses to accept the inaction of local enforcement. She knows someone is responsible for these crimes and wants some form of retribution. This ultimately comes in the form of FBI agent Tom White, who doggedly pursues the killer, unraveling Hale's conspiracy against the Osage in the process. White is entirely focused on making sure justice is served and conducts the investigation with great care. He is unswayed by Hale's local popularity, or the difficulty he faces in building a case against him. While Hale is ultimately jailed, Grann points out that many other murders like these occurred. These cases received no attention at the time and the killers faced no consequences for their brutality. The book ultimately seems to suggest that since these murders were only a fraction of the total—the majority of which went undocumented until now—justice was not, in fact, served.
Truth
Truth is another major theme in the book. The figures who are focused on justice, like Mollie and White, pursue the truth, even when it is painful or difficult. In contrast, people like Hale show no concern for the truth and consistently seek to twist it to their advantage. Hale and his men have no regard for the truth and care only about constructing a public narrative that benefits them. Similarly, Ernest Burkhart seems caught in his own deceptions, unable to own up to his betrayal of his wife. Grann himself is also greatly invested in giving a completely accurate account of the events surrounding the murder as he discovers, in writing the book, that there are numerous similar cases that went unresolved.
Corruption
Corruption is a prominent theme in the book. Grann portrays the prevalence of political corruption in Pawhuska, but also points out the broader corruption in American politics at the time. Hale is able to curry favor and exert influence in the community because he pays off local officials. Grann also explains how the Teapot Dome scandal profoundly shook the public's faith in the government, as it implicated President Warren G. Harding and showed how oilmen had used money and personal favors to broker for influence. Likewise, Hoover is portrayed in the book as primarily concerned with the outward appearance of the FBI, without worrying about the actual honesty of its practices. Hoover often spied on political opponents and celebrities with differing political views. The corruption of the period actively helps men like Hale, as it allows them to commit violence without facing punishment from a functional justice system.
History
History is also a key theme in the book. Grann shows how the Osage, even in the present day, try to maintain their traditions and acknowledge the past. When he goes to visit Pawhuska in modern times, Grann meets several of Mollie's descendants, who describe how they heard stories of the murders and the immense pain they caused for Mollie and other members of the tribe. The book concludes with Grann talking to Mary Jo Webb, an Osage tribe member who tells him that their land is saturated with the bloody past. For Webb, Mollie, and Grann, remembering these tragedies is an essential part of their history, as keeping them in circulation prevents them from being forgotten.
Evil
Evil is another of the book's central themes. While Grann gives the historical figures he writes about considerable depth and nuance, he does not shy away from labeling some of their actions as evil. He gives an unnerving description of Hale in prison in which he notes that he shows no signs of abnormal behavior, but displays no regret over his actions. Similarly, he makes note of the large number of similar cases, suggesting that the evil Hale was capable of was horrifyingly common.
