Martin Scorsese’s Killers of the Flower Moon at Apple is continuing to round out its cast.

According to Deadline, actors William Belleau, Louis Cancelmi, and Grammy Award winning artists Jason Isbell and Sturgill Simpson have all joined the cast of Oscar winner Martin Scorsese’s Killers of the Flower Moon.

The Apple Original film finds Scorsese reuniting with Oscar winner Leonardo DiCaprio, who will star in the forthcoming thriller.

Based on author David Grann’s New York Times bestseller of the same name, Killers of the Flower Moon is set in 1920s Oklahoma. The story centers on the FBI investigation of the murder of the Osage Nation— a tribe who winds up getting murdered one by one after oil is discovered on their land.

In the film, DiCaprio plays Ernest Burkhart, a member of a conspiracy lead by his uncle to gain control of Osage land by murdering members of the tribe.

For the film, William Belleau will take on the role of an Osage ranger named Henry Roan who has close ties to the Burkhart family. Louis Cancelmi will play a friend of Burkhart’s named Kelsie Morrison, who also happens to be a local hustler. Finally, Jason Isbell and Sturgill Simpson will take on the roles of Bill Smith and Henry Grammar, respectively. Bill is described as being one of Burkhart’s adversaries, while Henry is a rodeo champion and a bootlegger.

Behind the camera, Scorsese will direct and executive produce. Meanwhile, Forrest Gump vet Eric Roth will pen the script for the upcoming adaptation.

Currently, there’s no word on when we can expect to see Killers of the Flower Moon debut via Apple TV+.