In his third historical thriller, The Black Tower, Louis Bayard’s talent outruns his sensibility. Reading it is like being presented with a Hermes gift bag, only to find nestled within all the fancy paper a faux-leather purse from Wal-Mart.

In the early years of the French Restoration, when the Bourbons returned to power following the fall of Napoleon, a man is murdered in the streets of Paris while on his way to visit a poor and aimless young doctor named Hector Carpentier.

Soon Carpentier is drafted into the investigation by the famous criminal-turned-pioneering police inspector Vidocq. The two men—one a robust and brilliant master of disguise, the other timid—find themselves on the trail of a conspiracy to eliminate a young man who may be the surviving Dauphin, the rightful heir to the French throne, long thought to have perished in the forbidding prison called the Black Tower. 

It seems Carpentier’s father, also a doctor, had served Revolutionary authorities as the personal physician to the boy Charles, son of Louis XVI and Marie Antoinette, as he was being allowed to die in prison.  Yet a rumor persists that Charles did not die, but was smuggled out of the Black Tower, another boy set in his place. Vidocq and Carpentier locate a fair-haired country bumpkin of about 30 - the right age and appearance for the Dauphin. As they race to protect this adult Charles from persistent assassination attempts, they must unmask the conspirators while also discovering whether this strange man is the true king of France or another impostor.

A staff writer at Salon.com, Bayard is an elegant writer whose first two literary thrillers, Mr. Timothy and The Pale Blue Eye, were best-sellers. He has the skill to bring two past eras—post-Napoleonic France and the Revolution—into sharp relief in a single narrative. His story takes the reader into the brothels as well as the palaces of the renewed aristocracy.

Bayard is especially good with character. Vidocq brims with masculine life force. Charles is reminiscent of Chauncey Gardiner, the innocent in Jerzy Kosinski’s Being There. Carpentier’s unloving mother shows surprising shadings of personality, and a young prostitute reveals courage and competence without requiring a heart of gold.

But stylistic elegance cannot conceal a coarse narrative sensibility. Bayard is given to pretentious observations that underscore what’s already been conveyed by action: “In the end (and by now, you’ve figured this out) there is no forgetting. History lies low but always rises up.” A perceptive reader will be offended by such brazen authorial flattery. What’s worse, coincidence—that handmaiden of lazy plotting—plays too great a role in the developing action, and the resolution relies on not one but two instances of key characters, who conveniently look exactly like someone else.