Real life detective Vidocq was the first chief of the French Sûreté, an early 19th century crook turned cop who is generally considered to be the father of modern criminal investigation.  Here he’s presented as an often coarse, womanizing, egotistical, larger than life figure whose methods owe more to his criminal past than his respectable present, but with results that are successful beyond belief.  Hector Carpentier, a young doctor living in genteel poverty, comes within Vidocq’s orbit when a murder victim is found to be carrying a paper with Carpentier’s name and address. Hector, the viewpoint character for The Black Tower, has no idea why that should be, but Vidocq is not the sort to accept a "not my concern" brush off. He drags an unwilling Carpentier along with him through an investigation that takes them deep into dangerous secrets around the real life mystery of what happened to the Dauphin, subsequently Louis XVII. Louis-Charles supposedly died during the French Revolution, over 20 years before the setting of this book, while imprisoned in the Black Tower of the title. But since he didn’t die under public scrutiny like his parents on the guillotine, nor was there a public burial, rumors have circulated ever since that he somehow escaped. His own personal connection to the events of 20 years before will be almost as shocking to Hector as investigating their aftermath will turn out to be hazardous to his health.

This is an entertaining merger of real life people and events with pure fiction to create an historical thriller that equally emphasizes the history and the thriller. The barely catch your breath, secrets within secrets within secrets plot will keep you up all night to find the answers. Bayard’s literate but compelling style and colorful period detail bring the setting and people to life with vivid, "you are there" immediacy and credibility. Recommended, especially for people who usually avoid historical mysteries in the much mistaken belief that they’re all slow reading, thinly disguised history lessons.