Ray Levoi, a Federal Bureau of Investigation (FBI) agent, is partly Sioux Indian, although he has never acknowledged his Native American roots. When tribal council member Leo Fast Elk is murdered on the Bear Creek Reservation in South Dakota, the FBI director sends Ray there to join veteran agent Frank “Cooch” Coutelle. When Ray arrives, Cooch informs him that there is a “civil war” on the reservation between militant traditionalists, represented by the Aboriginal Rights Movement (ARM), and a pro-government faction called the Guardians of the Oglala Nation (GOON). Cooch takes Ray to the desert hillside where Leo Fast Elk’s body was found, and there they meet tribal policeman Walter Crow Horse. He wants to bury Leo’s body, but Cooch insists the medical examiner has jurisdiction. As the agents travel through the reservation, they encounter a roadblock, and Cooch introduces Ray to tribal president Jack Milton, who is stopping and searching vehicles of suspected ARM militants. At their motel, Cooch tells Ray about the leaders of ARM, particularly local schoolteacher Maggie Eagle Bear, and Jimmy Looks Twice, whom Cooch believes is Leo’s killer. Leading a team to a sweat lodge ceremony, they arrest Jimmy, but he quickly escapes, leading Jack Milton’s men to tear apart the houses of Jimmy’s acquaintances and damage Maggie’s schoolhouse. When Ray returns to the site where Leo’s body was found, he discovers Walter Crow Horse studying the area. Although Ray is derisive of Walter’s “Indian ways,” the tribal policeman insists the medical examiner will find red limestone in Leo’s wounds, even though it is located only in the bed of Little Walking River, near Maggie Eagle Bear’s home. He claims Leo was killed there, and his body was moved. Questioning Maggie, Ray learns that she and her children were in Rapid City, South Dakota, on the day of Leo’s death. He also meets her wheelchair-bound friend, Richard Yellow Hawk, and asks to question her grandmother, who was home at the time of the murder, but Maggie demands a warrant. Later, Cooch is angry that Ray did not record his conversation with Maggie. Walter Crow Horse informs Ray that Grandpa Sam Reaches, a respected elder and medicine man, wants to speak with him. Grandpa had a vision of Ray’s arrival, in which he learned from “signs” that Ray is chasing the wrong man. When Ray returns to Maggie’s house, she lets him talk with her grandmother. They claim their water is becoming contaminated, and Ray promises to help after he solves the murder. Maggie shows him the files of murdered ARM supporters, and asks him to investigate tribal funds controlled by Jack Milton. As they talk, trucks drive by and someone shoots into the house, injuring Maggie’s young son. Ray and Maggie rush the child to the local clinic, and, as the doctor attends to the boy, Ray spots the trucks outside. He beats up several of the men and handcuffs them. Howver, Cooch arrives with John Milton, insists that Milton is on their side, and claims ARM attacked Maggie because she is an informant. Cooch orders Ray to focus on catching Jimmy, and reveals that Grandpa Reaches is ARM’s spiritual adviser, so Jimmy will eventually seek his guidance. Later, Walter Crow Horse invites Ray to a ceremonial campfire on Grandpa Reaches’ property. Grandpa shares a vision that Ray and Walter Crow Horse must go to Red Deer Table together, but Ray refuses to believe in native mysticism. As he leaves, he encounters another roadblock run by Milton and his GOON crew. They let Ray pass, and he returns to the motel, where several officers are waiting. Cooch explains he assembled a field unit, and raided Jimmy’s hideout. Although Jimmy escaped, Cooch found the gun that killed Leo. Ray returns to stake out Grandpa Reaches’ home, and dreams of a graveyard. When he awakens, someone shoots his windshield. He reports the incident, and authorities search Grandpa’s trailer. As they drive away, Cooch and Ray encounter Walter Crow Horse parked on an embankment overlooking the river where he has found Leo Fast Elk’s missing car, half-submerged. Searching the vehicle, Ray finds a jacket whose pocket contains a raffle ticket. Ray visits Maggie, shows her the ticket, and asks if she still has the raffle list, because he believes the jacket’s owner is Leo’s killer. She tells him she is going to “the source,” and suggests he do the same. As he sits in his car, Ray has another vision of the graveyard, and finds himself running with several Indians as they flee a solider on horseback. As the soldier shoots him in the back, Ray awakens. He visits Grandpa Reaches to ask about the vision, and finds Jimmy there. The young Indian wonders why Ray and Walter Crow Horse have not gone to Red Deer Table as Grandpa asked, and reveals that Leo was murdered because he uncovered an illegal land deal. They are interrupted by the arrival of Cooch and FBI agents, who arrest Jimmy. Cooch declares the case is solved, and they can leave the next day. Grandpa Reaches joins Ray, and talks of the Wounded Knee massacre. Among the three hundred killed was a holy man named Thunderheart, whom the spirits sent to help his people, and Grandpa proclaims that Thunderheart’s blood runs through Ray’s veins “like a buffalo.” As Ray drives away, he sees the cemetery from his dreams. Inside, he finds the name Thunderheart on a marker commemorating those killed at Wounded Knee. When he returns to his motel, he finds that Maggie has left information that the wheelchair-bound Richard Yellow Hawk is the raffle ticket owner. Ray confronts Richard and learns he faked the disability as part of a deal. He was offered early release from Leavenworth Prison in Kansas in exchange for getting information on ARM. Richard confesses killing Leo, and reveals that Cooch was one of the FBI agents brokering his deal. Ray and Walter Crow Horse drive to Red Deer Table and discover test drilling sites for uranium. The Native Americans had voted against strip mining for years, but the government pushed them off the land, and John Milton received kickbacks to keep them away. Walter Crow Horse notes that Red Deer Table is the source of their water, and strip-mining will cause contamination. When they discover Maggie’s body, they see that she was taking samples at the drilling site before she was killed. Returning to Richard Yellow Hawk’s home, Ray and Walter Crow Horse find that he has also been murdered. Suddenly, several of Milton’s men arrive and ambush them. As Ray and Walter Crow Horse escape, Cooch and Milton give chase. Over the car radio, Cooch orders Ray to give up, but Ray reveals that he has a recording of Richard Yellow Hawk confessing Cooch’s involvement in Leo Fast Elk’s murder. Evading Milton’s roadblock, Ray drives into the desert toward the tribe’s traditional defensive stronghold in the rocks. Milton and his men surround them, and Cooch tries to negotiate, but Ray knows that Cooch has killed anyone who found out about the land deal. Insisting Cooch cannot kill everyone, Ray drops his gun and walks into the open. As Cooch takes aim, Grandpa Searches and dozens of Indians point their guns from higher ground, forcing Cooch, John Milton, and his men to surrender. Ray quits the FBI and plans to use Maggie’s media contacts to tell the story.