Dr Hector Carpentier is a partisan of no cause. His father, Dr Julien Carpentier, saw first-hand the ravages of the Revolution and remained resolutely impartial to politics. His son, cowed by his domineering mother and missing his deceased father, leads a very quiet life. Until he meets Vidocq, Paris' most legendary police officer.

Vidocq! Master of disguise and chief of a newly created plainclothes police force, Vidocq is a man whose name sends terror rippling through the Parisian underworld of 1818—and the inconsequential life of Hector Carpentier is violently shaken when Vidocq storms into it. A former medical student living in his mother's Latin Quarter boardinghouse, Hector finds himself dragged into a dangerous mystery surrounding the fate of the dauphin, the ten-year-old son of King Louis XVI and Marie-Antoinette presumed to have suffered a cruel death years earlier in Paris's dreaded Temple. But the truth of what happened may be even more shocking—and it will fall to an aimless young man and the most feared detective in Paris to see justice done for a frightened little boy in a black tower . . . no matter what the cost.

Welcome to Paris, c. 1818. After the execution of Marie Antoinette and King Louis XVI, and the death of their son, the Dauphin, the Bourbon monarchy has at last been restored. But a remnant core of Republicans is still working to fulfill the promise of the Revolution, and the great Napoleon is plotting his next return to power from the rocky exile of St. Helena. Partisans on every side will do whatever it takes to advance their causes. Dr. Hector Carpentier is a partisan of no cause. His father, Dr. Julien Carpentier, saw first-hand the ravages of the Revolution and remained resolutely impartial to politics. His son, cowed by his domineering mother and missing his deceased father, leads a very quiet life. Until he meets Vidocq, Paris' most legendary police officer. As founder and chief of the newly created plain-clothes force called the Surete, Vidocq has used his mastery of disguise and surveillance and his extensive knowledge of the Parisian underworld to capture some of France's most notorious and elusive criminals. And now he needs the help of the shy, provincial Hector Carpentier. Between the two of them, they may prove that the Dauphin, like Anastasia, lives, which could change the course of history.