Heirs to rival crime families, Johnny Shondell and Isolde Balangie have fallen in love and run away. As he seeks to unravel his complex 23rd case (following The New Iberia Blues), Detective Dave Robicheaux runs afoul of Isolde's father, a venomous New Orleans mafioso. Now Robicheaux is being trailed by a hitman who can induce horrifying hallucinations and travels on a ghost ship, and in order to defeat him and rescue Johnny and Isolde, Robicheaux will have to overcome the demons that have tormented him throughout his life.