Imagine investigating a case where each of the several victims had type O blood, drove an obsolete car, and hummed a nursery rhyme before committing murder and then suicide. That's young criminal psychologist Kit Franklyn's assignment, and the solution just seems plain impossible. Her obese, jovial boss, chief medical examiner Andy Broussard, is just as baffled as she is. Together they devise strictly scientific possibilities. Not once do they consider black magic to be the culprit until an ancient Cajun sorcerer's curse surfaces: "Beware the songs you loved in youth."