Indian agent Fred Carson is secretly the leader of a band of outlaws, using his official position to loot the U.S. Government if Indian allotment money. Aided by Ceta, the tribal Medicine Man, Carson directs raiding and robbing activities, both against the Indians and the local ranchers. Their hideout is on the Indian Reservation where a federal law prohibits local lawmen from following the outlaws. Carson's primary opposition is Indian Chief Yellow Wolf, who is aided by his son Blue Feather,and local doctor Jim Sterling, schoolteacher Doris Hammond and an old prospector named Nugget. They attempt to form an Indian Police Force with government backing, and draw up a petition, appealing to Congress for the authorization to enable the Indians to fight the outlaws on their own ground. After an attempt by Carson and Ceta to kill Blue Feather fails, Sterling, wearing an Indian face-mask, disguise himself as a Phantom Rider in order to wage a vigilante war against the outlaws.