In August 1785 Paris buzzed with a scandal involving an eminent churchman, a female fraudster, a part-time prostitute and the unpopular Queen herself. At the heart of the scandal was the most expensive diamond necklace ever assembled, and the tangle of fraud, folly, blindness and self-delusion it provoked. The humiliation inflicted on the royal family by this affair contributed to their appalling deaths in the Revolution just four years later.