Discharged naval officer Dan Corbett moves to New Orleans and accepts a job as a longshoreman, unaware that the docks are run by an infamous racketeer. When the dock manager is murdered before he can notify the authorities of their criminal scheme, Dan coordinates with the police to go undercover and investigate.

During the Civil War, in Wyoming, horse dealers Joan Britton and Stephen Cook are competing to supply the Union Army with horses. A Cherokee is in the area to stir up the Sioux against the Union just as Cook decides to steal a herd of Sioux horses. Ex-army doctor Jonathan Westgate opposes Cook’s unscrupulous methods as well as being Cook’s rival for the affections of Joan. It seems Westgate is the only one able to prevent a new Indian war.

Common efforts of the U.S. government and the Comanche nation to negotiate a peace treaty are sabotaged by renegade Indians and by the short-sighted Indian Commissioner.