During their journey back to Darkwood, Zagor and Chico arrive in New Orleans, Louisiana, which has only recently become American territory, just as Carnival is about to begin. But the festivities soon turn to tragedy: Donovan, commander of the city’s military garrison, is murdered in cold blood during the parade by someone disguised as Chico. The friendly Mexican thus becomes the prime suspect and is cleared only thanks to the intervention of Captain Ellis, an old acquaintance of Zagor.
From that moment on, the two heroes become unwittingly involved in the schemes of the Brothers of the River, a subversive organization seeking to transform the New Orleans region into a small independent, pro-French state. Zagor, Chico, and the young Captain Ellis set out to fight them, while also seeking the support of the local landowners.
After a series of ambushes and unexpected twists, the truth is finally revealed: the brotherhood was created by the local aristocrats themselves, led by the noble Alphonse de Marigny, who have been using their Black slaves as expendable pawns in their various attacks.
Zagor is captured and thrown to a huge alligator, but manages to survive and launch a counterattack. Fear then begins to spread among the rebels: the Lord of Darkwood is more than a match for all of them combined! And he has an unexpected ally on his side…
In a sudden change of allegiance, one of the young aristocratic “independence fighters,” Marcel Dutronc, joins Zagor in the final confrontation, which, thanks to the intervention of the American soldiers, ends successfully.
