Yancy wins enough money playing poker to pay for his return home to New Orleans. The losing players decide to rob him of his winnings, but he escapes on a riverboat.

City administrator Colton entrusts Yancy with an army payroll that is to be taken to Natchez on Yancy's riverboat, the Sultana, but robbers have other plans.

Yancy is relieved to find that a newspaper story about administrator Colton's death is premature, but fears that Colton will be the victim of trickery in an upcoming duel.

A mysterious mad bomber steals explosives and threatens to blow up the entire city of New Orleans.

Yancy must deal with a female pirate whose gang has stolen a valuable necklace from representatives of the Mexican government.

Merchants are in such fear for their lives that Yancy gets no cooperation in his attempt to break a new protection racket.

A visiting Russian noble appears to have become a target for murder.

With a serial killer loose in New Orleans and the authorities seemingly powerless, a group of vigilantes decides to take action before any more prominent women are murdered.

Yancy decides to help a fellow riverboat owner whose fleet is being sabotaged by rivals trying to corner the market on river traffic.

Yancy's Indian friend Pahoo becomes an important element in efforts to prevent a war with the Pawnee tribes.

On a train trip to a celebration of the completion of the transcontinental railroad, Yancy discovers a saboteur.