Jazz Tangcay Artisans Editor Based on the nonfiction book by David Grann, “Killers of the Flower Moon” stars Leonardo DiCaprio as Ernest Burkhart, a WWI vet who travels to Oklahoma to work for his wealthy uncle, William King Hale, played by Robert De Niro. It’s the early 1920s, and this part of Oklahoma sits on lots of oil, whose rights are owned by the Native American Osage and other tribes. They are prosperous, some even rich, and it’s here that Ernest meets Mollie (Lily Gladstone).