At the center of Burning Angel is Sonny Boy Marsallus, a fixer, a gambler, a lender of money to prostitutes who are trying to leave the life. But since Prohibition, the Giacano family has locked up the action in New Orleans and its surrounding parishes. When things get hot for Sonny Boy, he hightails it south of the border for parts unknown in El Salvador and Guatemala.

When Sonny resurfaces in New Orleans, Detective Dave Robicheaux of the Iberia Parish sheriff's office couldn't be more surprised - that is, not until Sonny passes him a mysterious notebook for safekeeping that seems to contain dark secrets about his activities in Latin America.

Robicheaux must wrestle with secrets closer to home as well when his help is enlisted by the Fontenot family, descendants of sharecroppers, whose claim to land they've lived on for almost one hundred years is jeopardized. Who wants the land so badly? And what of the longtime, clandestine affair between Moleen Bertrand, lord of the manor, and Ruthie Jean Fontenot, now reputed to be a local madam?

As Dave determines to find out who's honing in on the Bertrand spread, he puts himself in increasing peril at the hands of local mobsters and a hired assassin with a shady past that intersects with that of Sonny Boy Marsallus.