Martin Scorsese’s “Killers of the Flower Moon” is a bladder-buster of a movie with no obvious bathroom break, no section where the story starts to sag.

This makes it, almost by definition, a good and admirable piece of work.

但“Killers of the Flower Moon” is also a lumbering mess, an ungainly and tonally odd film that, for all the strength of its parts, has little cumulative impact.

Scorsese had ambitions to make a great American epic about the exploitation of Indigenous people, but he somehow ended up with a tawdry crime story, stretched to three and a half hours.

Based onDavid Grann’s2017 nonfictionbook of the same name, “Killers” tells the shocking real-life story of a series of brazen murders that took place in Osage County, Okla., in the 1920s. The Osage Native Americans had acquired considerable wealth from striking oil, but a white businessman named William Hale, while posing as a benevolent friend of the Osage, conspired to take their money.

In a scheme that would make Richard III look like a master of subtlety, Hale acquired inheritance rights to properties and then had the owners killed. And because all the local law enforcement was white and in Hale’s pocket, the murders — at least 20 of them — were barely investigated.

That’s compelling raw material for a movie, but there are two basic problems withScorsese’sapproach to it. The first is that he doesn’t fully understand the world he’s portraying and thus can’t use touches of humor to offset and accentuate the drama — though he does try.He introduces unexpected celebrity cameos and emphasizes moments of absurdity between Hale (Robert De Niro) and his nephew, Ernest (Leonardo DiCaprio). But such moments are jarring and seem weirdly off.

By contrast, in a movie set in New York, Scorsese always knows exactly why a rant by, say, Joe Pesci, can be simultaneously terrifying and hilarious. Here, Scorsese is lost in the prairie.

The filmmaker’s second problem, which is considerably more serious, is that he comes at the story from an odd angle. He doesn’t follow Hale, who is the villainous mastermind, and he doesn’t follow the federal investigator (Jesse Plemons) who is looking into the crimes. Instead, he follows Ernest, who marries Mollie, a wealthy Osage woman.

In a way, Ernest is a good role for DiCaprio, whose natural essence often leads him to playing shady, insubstantial guys who, all the same, have a conscience. Ernest is in love with his wife, even as he is working with his uncle to murder most of her family and eventually steal her money.

但是你怎么往下做一个中心人物h a person? If he’s just evil, that’s boring. If he’s an idiot, that’s even more boring. DiCaprio chooses to play Ernest as a weak-willed man in denial about the consequences of his actions. Being DiCaprio, he makes Ernest watchable, but he never quite makes sense of the man.

Clearly, Mollie is the character we really want to follow. She is the most purely good person in the film, as well as the wisest, and Lily Gladstone (“The Unknown Country”) gives a lovely, deep and moving performance in the role. Unfortunately, the movie’s adherence to the facts limits her screen time. In real life, Mollie was sidelined for much of the story, and so she must remain largely inactive.

Still, to be clear, all the above is just to break the news to you that “Killers of the Flower Moon” can’t and shouldn’t be confused for a great movie. But you can still feel good about seeing it.

One of our greatest filmmakers, at 80 years old, tried something new. Scorsese shouldn’t be penalized for our high expectations. Rather, he should be praised for making a movie that’s better than all right.

Reach Mick LaSalle: mlasalle@sfchronicle.com