Paris, 1794. Sir Percy Blakeney undertakes his most politically sensitive mission: removing Louis XVII, the imprisoned son of Louis XVI and Marie Antoinette, from the Temple. The plan depends on secrecy, discipline and the ability of the League to operate inside a city governed by suspicion. Armand St Just, however, allows his love for the actress Jeanne Lange to expose the conspiracy to Chauvelin.
Percy is captured and subjected to pressure intended to reveal the child’s hiding place and the names of his allies. Marguerite and the League must work around Armand’s betrayal while Percy turns apparent helplessness into another layer of deception. The novel places its fictional rescue attempt within the real imprisonment of the young Louis-Charles, making the struggle over the Dauphin a contest for Bourbon legitimacy as well as a personal test of loyalty.