Before there was Sherlock Holmes, there was Eugene Francois Vidocq, but unlike Holmes, Vidocq was a real criminal-turned-cop and the original plainclothes detective. In The Black Tower, Bayard takes advantage of the Frenchman Vidocq by using him to solve another infamous French crime, the murder of the boy king Louis XVII. Many people have laid claim to being Louis-Charles, son of Marie Antoinette and Louis XVI and all have been found frauds. Now there is a new claimant to that title whose assertions seem to be spurring some mysterious deaths. It is up to Vidocq and his reluctant sidekick Carpentier to find the murderer and to uncover the truth of the matter.
This is the second book I've read by Bayard and I'd say that while his characterization might not be the best, he's a solid author who does a good job of merging true history with fiction. I've got at least one more of his on my to-read shelf.