Nicolas Le Floch is going through a rough period: Louis XV is dead and Sartine has resigned from his post as Lieutenant General of Police to become Secretary of the Navy. Nicolas now works under the orders of a certain Le Noir and must investigate a murder committed at Monsieur de Saint Florentin's Mansion, minister to the new king.

Having just risen to the rank of police commissioner at the famous Chatelet in Paris, Nicolas Le Floch, a handsome young man from Brittany, is put in charge of investigating the murder of the young Viscount Lionel de Ruissec. But the viscount's family is thwarting the investigation, and doesn't want an autopsy. Le Floch discovers that the young man died after being forced to eat molten lead.

Nicolas Le Floch conducts an investigation into a spate of deaths by poison at the house of the influential M. de Montault. Before another poisoning occurs, he has to discover the identity of the mysterious enemy and what the motive could be for targeting de Montault family.

Paris is celebrating the Dauphin's coming of age by throwing a fireworks-filled party. Euphoric crowds eagerly await the celebrations, but police commissioner Nicolas Le Floch is worried: the incompetent Major Langlumé is handling security, instead of Royal Police Lieutenant Mr. Sartine. Nicolas' worst fears are confirmed when panicked revelers are crushed to death.

The Queen of France asks the curious Count of Saint Germain to give the Teardrop of Warsaw back its shine. If this pearl were to fade away, a terrible curse would strike the Monarchy. But the jewel has been stolen... and Nicolas Le Floch is in charge of the investigation.

Having just risen to the rank of police commissioner at the famous Chatelet in Paris, Nicolas Le Floch, a handsome young man from Brittany, is put in charge of investigating the murder of the young Viscount Lionel de Ruissec. But the viscount's family is thwarting the investigation, and doesn't want an autopsy. Le Floch discovers that the young man died after being forced to eat molten lead.

With the highly efficient help of Inspector Bourdeau, his second-in-command, and wise advice from Mr. de Noblecourt, a retired judge, Nicolas Le Floch uncovers a dark conspiracy. Caught up in a serious corruption scandal, the Count de Ruissec had recently had Army Lieutenant of Dragons Jean de Langremont killed, to silence him.

The young count Louis Charles of Allas is discovered beheaded. Nicolas le Floch, who has been sent to Aquitaine to investigate, discovers that there are other victims. Bourdeau, la Satin and Semacgus are his partners on this dangerous mission.

A mysterious prisoner dies while trying to escape from the prison of Fort-Lévêque. Nicolas le Floch's investigation on the murder of the stranger will lead him right in the middle of an espionage case involving the Minister of the Navy, Monsieur de Sartine, who will stop at nothing to establish the supremacy of the French fleet in the war against the English.

1777: France and England are at war over the independence of the United States. Nicolas le Floch, missioned by Louis the 14th to spy on the Duke of Chartres, who has his sights on the admiralty, witnesses the latter's cowardice in combat. He reports the facts to the king who nominates his cousin General of the light cavalry instead ... Le Floch has just made a mortal enemy out of him.