The Mancini Sisters, Marie and Hortense, were born in Rome, brought to the court of Louis XIV of France, and strategically married off by their uncle, Cardinal Mazarin, to secure his political power base. Such was the life of many young women of the age: they had no independent status under the law and were entirely a part of their husband's property once married.

Marie and Hortense, however, had other ambitions in mind altogether. Miserable in their marriages and determined to live independently, they abandoned their husbands in secret and began lives of extraordinary daring on the...