Benjamin January is hired to follow bank official Oliver Weems, who has fled New Orleans with money needed to save the school January and Rose established for freed people. They pursue him aboard the steamboat Silver Moon, travelling through a region where their legal freedom becomes increasingly precarious.
Weems is murdered before the stolen funds are recovered, leaving January trapped among slave traders, riverboat officers, confidence tricksters and political travellers. Working with the young planter Jefferson Davis, he must locate the missing money and expose the network of corruption around it before he or Rose can be seized and sold.