In 1849, during the California gold rush, prospector Jan Morell and his brother Frank plan to save enough gold in order to buy good farming land in the Napa Valley. One day, while Jan and Frank are prospecting in a nearby river bed, a gang of thugs and claim jumpers led by Jack Welch and Hank Purvis ransack Jan's cabin, steal his gold dust and kill his wife. One of the thugs, Purvis, also takes the cameo brooch Jan gave to his wife. When Jan and Frank return to the cabin and discover the tragedy, Jan swears vengeance. In town, at the local saloon, the killers spend their newly found gold loot at the gambling table. Jan and Frank arrive at the saloon where they start inquiring about the possible whereabouts of the gang who robbed them. The thugs are aware of this and decide to kill the two brothers upon their leaving the saloon. Frank is killed and Jan is wounded but manages to ride away. He is found by Mexican Felipe De Ortega who takes him to his home where his sister Elena nurses him back to health. The Ortegas tell Jan that a rich landowner named Thomas Ainsworth, owner of the Sierra Land Company, is the man responsible for all the land grabbing and claim jumping acts done in the region. Ainsworth, acting as regional mayor, opposes California's entry into the Union in order to avoid the eventual Federal law-enforcement, land management and insight into California's affairs. Ainsworth's hired thugs kill local farmers and steal their lands while he's bribing California's politicians to vote against joining the Union. The Ortegas also tell Jan that many farmers wronged by Ainsworth have formed a group ready to fight back. Jan decides to join the group and to fight against Ainsworth using Ainsworth's own ruthless tactics.