Restoration London, 1699 — Anastasia Ashby de la Zouche, Baroness Penge, Countess of Clapham, and former mistress to King Charles II, has astonishingly been jailed in debtors' prison. Joining forces with her loyal ex-maidservant, Alpiew, the formerly pampered and proper Countess sets out to make a living by working for the scandal sheets—a line of work that inevitably leads her through some of the seamier byways of the city. She and Alpiew find a welcome additional source of income when they are approached by a stranger who asks them to gather evidence to prove her husband is committing adultery. But the uncomfortable job of trailing after the handsome merchant in the depths of winter ends abruptly in a Covent Garden churchyard with a brutal murder. Implicated in the crime, the Countess and Alpiew find themselves drawn into a complex labyrinth of deceit, violence, and the mysterious world of alchemy. And the more they investigate, the more complex the picture becomes, involving everyone from the most decrepit back-alley criminals to some of the most influential people in all the land.

London 1700. The intrepid and impecunious heroines Countess Ashby de la Zouche and her maidservant, Alpiew, are scavenging for scandal for that scurrilous rag, the London Trumpet. With the bailiffs, as ever, in hot pursuit, the Countess and Alpiew escape to a philosophical lecture at the York Building's concert hall. But their dull evening is confounded when one player staggers onto the stage, hands dripping with blood. A doyenne has been decapitated under their very noses! The unlikely sleuths find an abundance of suspects: players, fanatics, a Punch-and-Judy man—not to mention a painter with a silver proboscis. They pursue their quarry from the Tower of London to Bedlam, with a brief detour to the wilds of Wapping, uncovering a shocking web of intrigue and corruption extending to the highest echelons of society and the judiciary.

The Countess Ashby de la Zouch would not be every parent's choice of chaperone for a beautiful teenager, still fewer would entrust her with finding the girl a husband. But the second Mrs. Alderman Franklyn-Green is willing to go to any lengths to get rid of her unwanted stepdaughter Virginia. The promise of 100 guineas and a sojourn in France is sufficient to secure the Countess' services, even if the girl is a complete shrew. Sadly, the exiled English Court at St Germain does not live up to their expectations. Worse, any hopes of enjoying fine French cuisine are dashed when a fellow guest is poisoned. Once more the Countess and Alpiew are plunged into a dangerous investigation, unraveling plots against three kings and negotiating the culinary eccentricities of the Court of Versailles.

Unlikely as it may seem, the Countess finds herself with cash to spare. Unlikelier still, she decides to do the sensible thing and invest it, caught up in London society's new craze for stocks and shares. Overnight, fortunes are being made, wealth amassed from nothing in a frenzy of speculation. And with these new-found riches anything can be bought: commodities, monkeys...even people. But as the Countess and Alpiew learn to their cost, investments can go down as well as up—helped along by a little embezzlement from those bastions of respectability, bankers and brokers. Soon banking leads to begging, burglary, and strange bedfellows—including an aspiring novelist with a grievance and a hirsute dwarf of astounding agility.