When a summer intern at the Preservation Society discovers an aged document hidden in the binding of an antique book, Society president Nell Pratt is intrigued by the possibilities: is it a valuable historic document or just a useless scrap of paper? When analysis reveals that it’s a hand-drawn map of one of Philadelphia’s oldest neighborhoods, Nell learns that the area is being excavated for a new real estate development and may hold long-buried secrets from the city’s historic heyday. Determined to get to the bottom of the map’s origin and what it might tell her about the mysterious plot of land, Nell will have to contend with a construction company owner who disappears, a former Society board member who’s harbored a dark secret her entire life, and a remarkable discovery that may have the dead turning over in their graves...