Anne Somerset: The Affair of the Poisons [2003] paperback

The Affair of the Poisons, as it was known, was a scandal at which ‘all France trembled’ and which ‘horrified the whole of Europe’ as it implicated a number of prominent persons at the court of the Sun King, King Louis XIV in the late 17th century. It began with the trial of Marie Madeleine d’Aubray, Marquise de Brinvilliers, who conspired with her lover, Godin de Sainte-Croix, an army captain, to poison her father and two brothers in order to secure the family fortune and to end interference in her adulterous relationship. The marquise fled abroad, but in 1676 was arrested at Liege. The affair greatly worked on the popular imagination, and there were rumours that she had tried out her poisons on hospital patients. She was beheaded and then burned. The Brinvilliers trial attracted attention to other mysterious deaths. Parisian society had been seized by a fad for spiritualist seances, fortune-telling, and the use of love potions.
The most celebrated case was that of La Voisin, a midwife and fortune-teller whose real name was Catherine Deshayes Monvoisin and whose clientele included the marquise de Montespan, Olympe Mancini (niece of Cardinal Mazarin and mother of Prince Eugene of Savoy), and Marshal Luxembourg. No formal charges were made, and there is no evidence that they were seriously implicated, yet a permanent stain was left on their names. La Voisin was burned as a poisoner and a sorceress in 1680. A special court, the chambre ardente [burning court], was instituted to judge cases of poisoning and witchcraft, and the poison epidemic came to an end in France. The affair was sympomatic of the witchcraft trials of the period throughout Europe. This bizarre witchhunt, which embroiled the gilded denizens of Versailles with the most sordid dregs of Paris society, remains both a fascinating enigma and an utterly compelling story.