Mac "Diamondback" Blackjack and his sidekick Moon haul cargo in their little sternwheeler - but the bulk of their living is made as white slavers, selling lovely young ladies to the gamblers and sod-busters living up-river. Maude is running away from the farm, seeking a life of excitement in old Orleans. Her plan is to hop a ride on Mac's riverboat, unaware of the true nature of his business. Mac is happy to oblige, and wastes no time breaking in "Muddy Maude." Maude, however, is none too happy with his disrespectful attitude, and teams up with Mac's three captives to plan a mutiny. Mac and Moon are forced off the boat, and the girls decide to turn it into a showboat. They all have a swinging time with their customers - and Maude gets sweet on Tim Sweetbreath. The future appears to be rosy ... but unbeknownst to the girls, Mac and Moon are coming back for reclaim their boat...