A group of men, lead by a questionnable sheriff and a wanted bandit, descend upon the desert in search of a lost canyon of gold.

In Arizona in 1874 there is a legend that the Apache gods store sacred gold in a hidden canyon. Marshal Mackenna of Hadleyburg learns the location of the canyon when he is ambushed in the desert and forced to shoot Prairie Dog, an old Apache chief. Before dying, the Indian gives Mackenna a map of the canyon but warns him that the Apache gods keep a vigil on the spot. After memorizing and burning the map, Mackenna is captured by a band of outlaws led by the ruthless Colorado, who has as his hostage Inga, a young Swedish immigrant and the daughter of the town judge. Aware that the marshal has seen the map, Colorado threatens to murder Inga unless Mackenna leads him to the canyon; Mackenna reluctantly agrees. Before long the band is joined by a group of Hadleyburg citizens who have also caught "gold fever." This group is pursued by Apache warriors who want to use the gold to fight the white man, and by a U. S. Cavalry troop tracking Colorado. The warring factions clash, and the only survivors are Mackenna, Colorado, Inga, and two renegade Apaches--the seductive Hesh-Ke and Hachita, a silent brave. They are soon joined by Cavalry Sergeant Tibbs, who has murdered his own men in order to search for the gold. As the fortune seekers make their way toward the canyon, Hesh-Ke becomes enraged by Mackenna's attentions to Inga and is killed trying to murder her rival; Hachita, believing the Apache gods are angry, kills Tibbs but in turn is slain by Colorado; and Colorado, now that he has found the treasure, engages Mackenna in a death struggle on a narrow ledge. The battle is interrupted by Apaches; their stampeding horses start an avalanche that obliterates the canyon and buries the gold. Only Mackenna, Colorado, and Inga escape. Vowing someday to find and kill Colorado, the unarmed Mackenna rides away on Sergeant Tibbs's horse, its saddlebags filled with gold.