David Grann’s Kirkus-starred 2017 true-crime book, Killers of the Flower Moon: The Osage Murders and the Birth of the FBI, tells the riveting story of how several members of an Osage family in 1920s Oklahoma were murdered in a plot by a wealthy white businessman and his accomplices to get control of the family’s oil wealth. Unfortunately, a new film adaptation—directed by Martin Scorsese and starring Leonardo DiCaprio, Robert De Niro, and Lily Gladstone—focuses primarily on those white men, instead of on the people they killed. It premieres in theaters nationwide on Oct. 20.

Starting in 1907, every enrolled member of the Osage nation was given a “headright” that entitled them to a percentage of royalties paid by oil companies who leased oil-rich Osage land; these rights couldn’t be bought or sold, but they could be inherited. By the ’20s, the enrollees were enormously wealthy, and white Oklahomans were scheming to get at this money, often by marrying into Osage families. In some cases, these whites orchestrated the murders of their spouses—often making the deaths look like accidents—to get full control of the headrights for themselves. Grann’s book focuses on one extended Oklahoman Osage family that was nearly eradicated by such a plot: Mollie Burkhart’s mother, sisters, and first husband were all killed in a plan set in motion by local white political boss William Hale. Hale was assisted in his scheme by Mollie’s husband, Ernest Burkhart, who was his nephew. Mollie herself was poisoned and very nearly died.

Hale’s crimes were eventually uncovered by a team led by ex–Texas Ranger Tom White, a federal agent of the Bureau of Investigation (later known as the FBI); he’s ably played by I’m Thinking of Ending Things’ Jesse Plemons in the film. In Grann’s book, White is a major player—one chapter is devoted entirely to his backstory—and Scorsese, in a recent New Yorker interview, noted that his original vision for the movie had White as the main character. DiCaprio, he said, urged him to make Ernest the lead player, instead. (There was apparently no discussion about making an Osage character the focus.)

It shouldn’t come as a surprise that Scorsese—the filmmaker behind Mean Streets, Taxi Driver, Goodfellas, The Wolf of Wall Street, and The Irishman—is more interested in this story’s criminals. Hale is accurately portrayed as a calculating and remorseless killer, and De Niro, in fine form, chillingly plays him as such. But Ernest, his willing accomplice, is cast in a much more sympathetic light. As portrayed by DiCaprio, he’s a not-too-bright guy who comes under the sway of the smarter, more forceful Hale. He also seems to care about Mollie, despite the fact that he’s poisoning her on his uncle’s orders, and ultimately shows regret for his actions. The real-life Ernest, as depicted in Grann’s book, was nothing more than a murderous thug—hardly worth the attention that Scorsese and DiCaprio lavish upon him.

Gladstone, who plays Mollie, was a highlight of the FX show Reservation Dogs, in which she played a minor but memorable role, and she delivered a heartbreaking performance in Kelly Reichardt’s Certain Women. She’s quietly remarkable here as well, offering subtle, nuanced work that puts DiCaprio’s scowling, twitchy performance to shame, despite the fact that she has relatively little to work with. Scorsese and co-writer Eric Roth (Forrest Gump) don’t seem to have given much thought to her character, other than how she fits into Ernest’s unearned redemption arc.

Why didn’t Scorsese focus more directly on Mollie and the Osage people, whose story this actually is? The film does spend time documenting aspects of Osage culture in events such as naming ceremonies, a wedding, and multiple funerals. But it spends far more time with Ernest and Hale, which feels misguided. Grann’s book points out that “the evil of Hale was not an anomaly”; there were many similar murders around the same time, most of them unsolved. He quotes Osage County resident Mary Jo Webb, whose grandfather may have been one of those victims, as saying that the “land is saturated with blood.” That’s the real story of Killers of the Flower Moon—but in this movie version, it’s drowned out by white noise.

David Rapp is the senior Indie editor.