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.

During the reign of the young Louis the XVI, Nicolas Le Floch must struggle through terrible events, political and personal alike. Back from a mission in Vienna, he finds Paris in an uproar: the bakers' blood. With the support of the king and the help of his faithful friends, he investigates the suspicious murder of a baker that soon leads him to suspect a plot.