The Black Dakotas

Opening narration explains that Confederate agents are sowing discord in the West to draw Union troops away from battles in the east. The plan is to incite Indian tribes against the federal government. This setup foreshadows the frontier conflicts that drive the plot.

During 1864, a stagecoach is attacked and the driver is killed. Zachary Paige offers his money to the attackers, but they reveal they want his diplomatic mission to the Sioux. Brock Marsh, a Confederate agent, plans to impersonate Paige and betray the treaty, and he shoots Paige to protect the mission.

Marsh arrives in the nearest city under Paige's identity and reports his mission to local authorities. Gimpy Joe Woods offers help, but Marsh selects Daugherty to escort him toward the Sioux. A lynch mob convenes an improvised court and hangs John Lawrence for treason, while Ruth Lawrence vows revenge; Gimpy reveals himself as Lawrence's second in command and questions Marsh's choices.

Daugherty warns Marsh that War Cloud's son Black Buffalo seeks extermination of whites. A war party led by Black Buffalo attacks, and Marsh's ally is killed; Marsh is captured. He remains defiant but is taken out of the fight, signaling a grim turn in the mission.

Marsh is forced into a fight to the death with a Sioux brave. He defeats the warrior by throwing his knife, buying time for a rescue by Daugherty's posse. The escape comes just as the odds turn against him.

Back in town, investigators uncover the real Paige's body from a shallow grave marked with his name. Marsh denies having a traveling companion, trying to maintain his cover. Gimpy fires on the town marshal and judge from an open window, killing them and turning the townspeople against Ruth.

Gimpy confronts Ruth, confirming her innocence about the sheriff/judge killings. He and his cohort ride away with Mike (unconscious) and Ruth, taking them toward their own camp or allies with the Confederates.

Marsh arrives at the Sioux camp and meets Chief War Cloud to discuss the treaty. He presents a signed copy offering gold as payment, and War Cloud gives him three days to deliver the gold.

Ruth talks with the Confederates about the stagecoach plan and explains that the gold will be used to support the Confederate cause. The Confederates weigh the opportunity against the risk of exposure.

A messenger reveals the stage's location, three hours behind. Ruth feeds Mike and frees him; Mike escapes on a horse and quickly informs Ruth of the new movement.

Marsh and three Confederates ambush the stage, killing the soldiers and taking the gold. Ruth arrives with a shotgun but is overpowered by Marsh; Gimpy is killed and Marsh secures the gold. The Sioux arrive and free Ruth.

Mike pursues Marsh and defeats him in their confrontation. He then presents the treaty and the gold to War Cloud, who signs the treaty, ending the conflict.