Kirby Buckner, engaged in gambling and other activities in New Orleans, receives a cryptic warning from an old African-American woman: "Trouble on Black River!" Understanding the significance, Buckner immediately returns to his home in the isolated backcountry between Black River and Nigger Head Creek. This region, characterized by its pine forests, swamps, and independent inhabitants, has its own laws and traditions.

Upon arriving at the steamboat landing, Buckner rides to the village of Grimesville, crossing Nigger Head Creek, named after a violent rebellion where the leader's head was nailed to a tree. During his journey, he encounters a mysterious quadroon woman with a Spanish accent who tries to lure him into the woods. When he resists, he is attacked by three African-American men. Buckner defends himself with dueling pistols and a bowie knife, managing to kill one and wound another before the third flees.

At dawn, Buckner meets Esau McBride, a villager investigating the gunshots. McBride informs him of the recent strange behavior among the African-American villagers on Cypress Creek, who have been influenced by Saul Claver, a charismatic figure from South Carolina, and his brazen female companion. The villagers speak of drums and chants emanating from the swamps, signaling wild and possibly sinister rituals.