Paris, 1774. Commissioner Le Floch's stormy love affair with socialite Julie de Lasterieux has run its course but before Nicolas can formally end the relationship, Julie is found murdered in her bed, a victim of poisoning. For now, he retains the confidence of even the King, who sends him on a secret intelligence mission. But a plot is afoot to implicate Nicolas in Julie's death, and he is soon fighting to uncover the perpetrators and clear his name.