James Garner appears as a civilian guide through Indian territory and Bill Travers as an 'uptight' cavalry lieutenant escorting an ammunition shipment to a distant and isolated fort. Also on the trail with them is a retired army sergeant (Sidney Poitier), now breaking in military horses, and Travers' wife (Bibi Andersson), a victim of rape by Apaches. Her 'half-breed' child is the subject of ongoing racial tension. And Garner, who once had a Comanche wife, is bent on vengeance for her scalping. As this caldron of moving tension travels through the West, they will be beset by a series of violent Indian attacks.