New Orleans police detective Dave Robichaud is familiar with both the dangerous bars of the French Quarter and the treacherous swamps of Louisiana, along which the secret trails of drug dealers pass. When Robichaux discovers the body of a prostitute in the bay, he unknowingly walks into a deadly trap. He becomes a target for the mafia and corrupt police officers. The hunt is on, and Vietnam War veteran Robicheaux must solve the complex crime before the violent thunderstorms of the southern summer wash away the blood from the city streets.