Robert de Niro and Leonardo DiCaprio in 'Killers of the Flower Moon' (Apple)

First Look at De Niro and DiCaprio in 'Killers of the Flower Moon,' Martin Scorsese's Western Crime Epic

Leonardo DiCaprio and Robert De Niro are headed to 1920s Oklahoma in the first trailer for Killers of the Flower Moon, the upcoming crime epic from Academy Award-winning director Martin Scorsese. Based on David Grann's 2017 history Killers of the Flower Moon: The Osage Murders and the Birth of the FBI, the period drama tells the true story of the so-called Reign of Terror, in which more than 60 Osage Nation tribe members were murdered over oil rights. Top supporting cast members include Jesse Plemons (The Power of the Dog) and Certain Women's Lily Gladstone, along with country stars Sturgill Simpson and Jason Isbell.

Videos by Wide Open Country

The first trailer for Killers of the Flower Moon, in theaters October 20, introduces DiCaprio's Ernest Burkhart, who's married to an Indigenous woman named Mollie (Gladstone). "There are many, so many, hungry wolves," DiCaprio says in voiceover to scenes of Osage Nation tribe members being terrorized and killed. We glimpse De Niro as William Hale, Burkhart's uncle and a high-powered Oklahoma rancher, as well as Plemons' FBI Agent Tom White, the lead investigator in the Osage Nation murders.

With a script from Scorsese and Oscar-winning Forrest Gump screenwriter Eric Roth, Flower Moon dramatizes the discovery of oil on Osage Nation land, which prompts wealthy oil barons to systematically kill the Osage. The murders sparked one of the first major FBI investigations, even involving storied FBI Director J. Edgar Hoover, a role DiCaprio took on in Clint Eastwood's 2011 biopic J. Edgar.

Lily Gladstone and Leonardo DiCaprio in Killers of the Flower Moon. (Apple)

De Niro and DiCaprio are frequent Scorsese collaborators, and Flower Moon marks the first time all three have worked together on a film. De Niro has starred in such Scorsese classics as Taxi Driver and Raging Bull (for which the actor won an Oscar), most recently leading the director's Netflix mob epic The Irishman. For his part, DiCaprio received Best Actor Oscar nominations for his starring roles in Scorsese's The Wolf of Wall Street and The Aviator.

Robert De Niro and Jesse Plemons in Killers of the Flower Moon. (Apple)

Other cast members include John Lithgow, recent Oscar winner Brendan Fraser (The Whale) and Grammy-winning country artists Sturgill Simpson and Jason Isbell. The stacked ensemble also features critically-acclaimed Indigenous actors Tatanka Means (Reservation Dogs) and Tantoo Cardinal (Wind River), as well as William Belleau (The English) and newcomer Cara Jade Myers (Rutherford Falls). Scott Shepherd (The Last of Us), Louis Cancelmi (Billions) and Pat Healy (George & Tammy) round out the cast.

Killers of the Flower Moon is in theaters everywhere October 20.

READ MORE: First Look at 'Dark Winds' Season 2: A Serial Killer, a Femme Fatale and a Deadly Secret