Gambler Oak Miller seeks revenge on the man who misused his sister Rose, who is ill and under the care of the woman Oak loves, Barbara. The man Oak seeks, Granger, is planning to rob a wagon train with the collusion of the Indians under Chief Long Knife. When Barbara is suspected of killing her lascivious stepfather, Oak takes the blame and is arrested just before he is needed to save the threatened wagon train.

Sent by the Army, Andy Thomas poses as a renegade to find out who has been harassing the wagon trains.