A former royal mistress and her loyal companion find themselves entangled in a murder investigation after a routine surveillance job turns lethal in 1699 London. Anastasia Ashby de la Zouche, a disgraced Countess, must navigate the harsh realities of life outside the palace walls to survive. Alongside her sharp-witted former maid, Alpiew, she attempts to earn a living through investigative work for scandal sheets. Their objective shifts from simple surveillance to clearing their names when they are framed for a brutal killing in a Covent Garden churchyard. The narrative follows their movement through the rigid social strata of Restoration England, where they encounter both destitute criminals and powerful elites.

Readers frequently highlight the sharp, witty banter between the Countess and Alpiew as a primary draw of the series. Discussion often centers on the vivid depiction of 1699 London, noting the contrast between the grime of the streets and the opulence of the aristocracy. Critics often point to the balance of historical atmosphere and traditional mystery tropes, which keeps the pacing brisk. Many readers appreciate the unconventional nature of the protagonists, who operate outside the typical societal expectations of their time. The integration of alchemical lore adds a distinct layer to the investigation that distinguishes it from standard historical procedurals.