Inadecayingplantationgraveyard,AlanGrahamfindsacluetoagreatAmericanmysteryTheheadstonereadsLouis,andwhenPepperCourtneyfindsit,sheassumesitbelongedtoaslave.Butwhentheoldwomanwhoownsthecrumblingplantationhousegivesheranancestor'sdiary,CourtneydiscoversthatLouiswasawhitemanwhosedrifter'sappearanceconcealedagentleman'smanners.Whowasthisstranger,andwhydidhediewiththepresident'snameonhislips?Courtney'sboss,contractarchaeologistAlanGraham,hasaradicaltheory—andtherearethosewhowouldkilltokeepitquiet.Basedonthediary,thedig,andthescanthistoricalrecords,GrahambelievestheheadstonemayhavebelongedtoexplorerMeriwetherLewis,whowassaidtohavediedinTennesseebutmayhavesurvivedtomakeanewlifeinLouisiana.Tosolvethiscenturies-oldmystery,hewillhavetocatchamodern-daykiller.