The Osage Indians called the murder spree the Reign of Terror. In the early 1920s, some two dozen men and women of the Oklahoma tribe were killed. Well-meaning whites who tried to bring justice to the Osage also were killed. Only the intervention of the FBI and its hard-charging new director, J. Edgar Hoover, ended the crime wave and brought the perpetrators to justice.

In “Killers of the Flower Moon: The Osage Murders and the Birth of the FBI,” David Grann, a staff writer at The New Yorker and author of “The Lost City of Z,” brings his acclaimed storytelling powers to this sinister true story of corruption, death, secrets and shadows. Grann’s reporting and archival sleuthing ballast a powerful account, which, at its best, evokes the noirish worlds of the movies “Chinatown” and “L.A. Confidential.”

Like the water in “Chinatown,” another precious commodity — oil — prompted the bad deeds here. The rocky, barren terrain of northeastern Oklahoma, where the Osage were pushed by the U.S. government in the 19th century, actually sat atop a vast reservoir of oil, which by the early ’20s had made the tribe fantastically rich. And, as Grann reveals, targets for murder.

Among them was the family of Mollie Burkhart, whose mother, Lizzie, was poisoned. Then her sisters perished: Anna Brown was found shot to death in 1921, and the house of Rita Smith and her husband was bombed in 1923. Corrupt local authorities made little headway. Bad police work — botched autopsies, lost evidence, buried leads — was a deliberate strategy, Grann suggests, to shield the killers.

The Osage implored the federal government to intervene. The initial FBI investigation faltered until Hoover, fearful of a scandal and looking to expand his power, brought in Tom White, a former Texas Ranger whose skills proved vital to the investigation. White found himself up against a mountain of hearsay and misinformation, “his work more akin to espionage than to criminal investigation.” The dearth of concrete evidence left many cases unsolved. But White’s team of undercover operatives, with the help of criminal informants, homed in on the murders of Brown and Smith.

What White discovered was troubling, and pointed directly to Mollie’s own husband, Ernest, a white man.

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Grann does an admirable job explaining the fiendish complexities and racial undertones of what happened, and the role oil played in the plot Ernest and his brother, Bryan, concocted with their powerful rancher uncle, William Hale, the “King of the Osage Hills,” who posed as a friend of the Indians.

In reality, he was a monster. Hale commissioned the killings of Mollie’s family in an attempt to direct their oil rights, which could only be inherited, into Mollie’s possession, and thus to Ernest on her death. Hale also was implicated in several other murders.

The resulting trials were headline-makers. But this is only the beginning of Grann’s revelations. With the convictions of Ernest Burkhart and Hale, the FBI considered the Osage matter, which Hoover used to show off the prowess of the bureau in its first major homicide investigation, closed. But for the Osage themselves, questions remained.

The last section of “Killers of the Flower Moon” is a haunting exploration of the legacy of these crimes, and a first-person account of Grann’s encounters with Mollie’s granddaughter and other tribe members, as well as his exacting, even fanatical, research. As Grann discovers a pattern of mysterious deaths that extends far beyond the official tally, a sense of creeping dread takes hold of the reader and never lets go.

It was all mixed up with the murk of the so-called “Indian business.” The federal government exercised tyrannical control, down to the penny, over how the Osage spent their funds. Guardians — prominent white citizens, ranchers, politicians and lawyers, men like William Hale — oversaw a system that left some of its wards in dire need. ‘Your money draws ’em and you’re absolutely helpless,” one Osage told a reporter in the ’20s. “They have all the law and all the machinery on their side.”

Grann’s closing pages are gripping — and downright frightening. Poring over ledgers and other records, Grann finds an unnaturally high rate of death among the Osage. Some died from natural causes; but many more, the author very plausibly argues, by nefarious means. Hale “might have led the bloodiest and longest killing spree. But there were countless other killings . . . [that] were never investigated or even classified as homicides.” In “Killers of the Flower Moon,” malevolence itself stalks the land.