Pierre de Siorac, a freshly minted physician and Huguenot, has survived the St. Bartholomew's Day Massacre with the help of friends and returns to Paris two years later. King Henry III has appointed him as his personal physician, but soon he becomes primarily the king's secret agent on sensitive political missions. France is still a deeply divided country, with the Catholic League, led by the powerful Duke of Guise, opposing the king, who is trying to mediate between Catholics and Protestants for the sake of the state. Spain supports one side, while England backs the other. The deadly duel between Henry and Guise dominates French politics for over a decade. Disguised as a cloth merchant, a master tailor, or a royal bodyguard, Pierre travels across the country, facing adventures, duels, and assassination attempts, encountering spies and counter-spies. He travels to Henry of Nava.