The odd lovely moment slips into “Killers of the Flower Moon,” Martin Scorsese’s grim and epic treatment of a systemic mass murder of Osage Indians for oil rights in 1920s Oklahoma. But then, when you’re Martin Scorsese and you put 206 minutes on the screen, something beautiful is sure to get in, if only by accident.

Scorese’s most indulgent film since the bloated gangster epic “The Irishman,” but with echoes of the patience-puncturing “Silence” and “Kundun,” “Flower Moon” is an intimate and detailed immersion in a horrific, slow-motion crime committed by a predatory political boss and his henchmen to manipulate, marry and even murder tribe members on “Indian land” that was rich with Oklahoma Crude.

It is forgotten “erased” history in the American epoch of manifest destiny and unfettered capitalism, and as such, it is designed to frustrate. Who are the “good guys” here? Who do we root for? Is justice coming, or at least comeuppance?

But the frustration extends to the “streaming length” “Netflix editing” of this bloated low-boil movie. Even with his trusty and equally-seasoned editor Thelma Schoonmaker — she, like Scorsese, is over 80 — the director of “Wolf of Wall Street” and the long and breathless “The Departed” turned in a cut nearly three and a half hours long.

Depending on how ruthless you are with repetition, excess coverage, scenes that add “color” but do nothing to advance the plot and indulgent pauses for self-conscious acting mannerisms (Jesse Plemons, take a bow, but blush when you do), this beast is burdened with 45 minutes or as much as 75 of pace-killing, story-deadening filler.

The film begins with a poetic prologue of oil discovery straight out of “The Beverly Hillbillies,” and follows that with a  SECOND prologue of mock (and real) newsreel accounts of the richest people in America in the Jazz Age 1920s, the luxury-car (Pierce Arrow) luxury-goods buying Osage of Oklahoma.

I mean, I LOVE Scorsese. But come on. Choose ONE prologue.

I couldn’t stop thinking “Heaven’s Gate” as this crime-spree-as-saga unfolded, another tale of the unpleasant truth about America and The West. But that, at least, was burnished with the glow of grandeur, gorgeous images and compositions, production design that looked epic and lived-in, even if, like “Flower Moon,” it’s a tale where it’s hard to find somebody to root for.

We meet Ernest Burkhart, in uniform as he steps off the train in Fairfax, Oklahoma shortly after World War I. Played by a paunchy, 1920s dentistry version of Leonardo DiCaprio, Ernest is a man of simple wants and simple skills. He was a cook in the Army and ruptured himself so he can’t do manual labor any more. And “I love money.”

But not to worry, his uncle, the “King of Osage County,” rancher and deputy sheriff William “King” Hale (Robert DeNiro) can hook him up. There’s work, sure. But the money is with the Osage tribe, where the free-spending men are ripe for robbing, and women with a “full blooded stake” in their oil wealth, control of “head rights,” are there for the marrying.

The Osage are dying, and under suspicious circumstances, the viewer learns and Ernest eventually figures out. But not until after he’s met and taken a shine to fair Mollie Kyle. She’s played with a quiet, modest inscrutability by Lily Gladstone of “First Cow” and TV’s “Billions.”

Ernest finds himself smitten and ingratiated into the 25 families of Osage who supposedly hold the power in the place. But he’s also tangled up in his uncle and ruthless brother Byron’s (Scott Shepherd) assorted “jobs” related to procuring “head rights.”

In scene after scene, we see patronizing white banker “guardians” who make Mollie and others identify their status as “incompetent” when coming to them for their cash, unscrupulous doctors who “treat” Native Americans who all die by 50, many much younger, paternal King Hale and workers, servants and others who glower at the money the Osage have “but didn’t ‘earn.'”

Mollie, chatting in Osage about the white WWI veteran’s attention, acknowledges that this “coyote wants money.” “But he wants to be settled,” too. She warms to him.

It’s only after the marriage that we see the degree the Osage have been dehumanized by the racists in charge, and that worries about The Klan getting a foothold there are nothing, because the whole white power structure of the place is into killing Indians for profit.

The story is designed to frustrate because we keep waiting for conversions, characters to grow a conscience, for “The System” to protect victims from predators. Not in the unfettered 1920s, friends.

Tribal elders are at a loss. The days of Indian Wars are long past, they are few in number and now they’re being murdered with “no investigation,” one by one for this wealth they stumbled into.

“We can’t talk to the County” about this, one complains. “We can’t even go to The State of Oklahoma.”

And approaching President Laissez-Faire himself, Calvin Coolidge, seems as futile as it is desperate. But there’s this new tool in the Justice Department, the (Federal) Bureau of Investigation. That’s how ex-Texas Ranger Tom White (Plemens) is brought to town.

The leads are quite good, even if it seems DiCaprio is taking pains to sport the same puffy scowl, first scene to last. Other performances have an untrained-actor documentary reality about them, and some are “Come on, give the poor fellow another take” clumsiness. John Lithgow and Brendan Fraser are brought in for third act legal histrionics.

The music, musician cameos and period details are great, and I loved the way Scorsese stages the “Here’s what happened to everybody” epilogue, as a 1940s radio drama’s closing summation.

But the film is frustrating in unplanned ways, too. He’s made a grossly-under-edited picture too ready for its Apple TV+ afterlife, a drag that becomes an endurance contest without the dramatic flourishes to make anybody want to pause streaming it when they leave the room for a toilet break.

Compare this to Christopher Nolan’s flashy and brisk and quite long “Oppenheimer” and you’ll understand the difference between long and engrossing, and just long and wearing.

As with Cimino’s The West at its Ugliest “Heaven’s Gate,” Scorsese has delivered an ordeal pretty much guaranteed to leave a bad taste in your mouth, one that in this case plays as pedestrian and repetitive, and never feels like an “epic.”

Rating: R for violence, some grisly images, and language

Cast: Leonardo DiCaprio, Robert DeNiro, Lily Gladstone, Jesse Plemons,
Tantoo Cardinal, Tatanka Means, Brendan Fraser, Yancy Red Corn, William Belleau and John Lithgow.

Credits: Directed by Martin Scorsese, scripted by Eric Roth and Martin Scorsese, based on the book by David Grann. A Paramount release.

Running time: 3:26