THE eternal question for film adaptations is whether it's better to see the movie or read the book. With Killers Of The Flower Moon, the answer is yes.

You'll get a very different experience, whichever way you go. David Grann's nonfiction book is a whodunit: In the 1920s, the Osage people in rural Oklahoma died in alarming numbers, likely related to the fact that they were oil-rich.

In Martin Scorsese's movie, we know from the beginning what's happening: White men are marrying Osage women and slaughtering their families so they can inherit their wealth.

It's a subtler approach – I guess it's not surprising that "subtle" describes a movie that's three-and-a-half hours long – and it pays different dividends. Whereas Grann makes the Osage seem clueless, the movie gives them more wherewithal. Shortly after Mollie (Lily Gladstone) falls for Ernest Burkhart (Leonardo DiCaprio), she comments, "Of course he wants our money, but he wants to be settled."

The big question in the movie is: Does Ernest love his wife, even as he schemes to eliminate her family, doing the bidding of smilingly vicious crime lord William Hale (Robert De Niro)?

Well, you did say we should start our own fan club.

That makes the evil at the centre of the story more shocking because it's not a case of something awful happening but nobody can figure out what it is. It's that something awful is happening and almost everybody knows what it is but the Osage can't convince anyone to care. (When word gets to Washington DC, Killers Of The Flower Moon becomes the first movie in history to depict President Calvin Coolidge as a hero.)

Much has been made of Scorsese shooting this solemn epic in Oklahoma with a largely Osage cast. That care pays off because, riveting as the book was, the movie makes more sense.

Time feels like it accrues over the course of a double-length movie and having the clues fall into place earlier better suits the fact that these were crimes committed by fools who didn't know what they were doing.De Niro is entertainingly nasty and Jesse Plemons is stoically heroic as an FBI agent, but the crux of the movie is one of the oddest romances since Holly Hunter and James Spader did it with cars in Crash.

You know, my next Oscar would look great on that shelf up there.

DiCaprio may genuinely love his wife, even as he poisons her in what plays like a marital version of Munchausen syndrome. And Mollie loves Ernest, although she's too smart not to suspect what's going on. If we're in love, Killers Of The Flower Moon seems to say, we can convince ourselves of anything.

Gladstone, so memorable in Certain Women, maintains the mystery of Mollie, who is kept off balance by not just the poison but the grief of losing her whole family. She and her fellow Osage characters are central, but it remains DiCaprio's movie.

Ernest is an unusually passive, foolish character for a big-time actor to play, but in later scenes, when Ernest begins to understand what's going on, DiCaprio takes him into bold, almost Billy Bob Thornton-as-Sling-Blade territory.

Until an ending that finds a surreal way to tell us the final fates of these real-life "characters," Killers Of The Flower Moon is a handsome, almost stately movie. Scorsese is a great stylist, but he takes a back seat, insisting that we give this forgotten story the attention it has deserved for the past century. – Star Tribune/Tribune News Service