Palermo 1632: Giulia is thirteen when she learns her mother greatest secret: Teofania makes an undetectable, slow-acting, lethal poison--Acqua Tofana--which she uses to free the broken and abused women of Palermo. Now Teofania wants to pass her recipe on to her daughter, and Giulia soon realizes that in a time when women have no voice, justice is sometimes best served in a cup of wine or broth.
Rome, 1656: Years later, within the alleys and shadows of the Eternal City, Giulia forms her own circle of female poisoners, who work together under the guise of an apothecary shop to sell poison to women in need.
But even in a time of plague, when death looms over the city, it doesn't go unnoticed that the men of Rome are starting to fall like flies. And with the newly elected pope determined to rid the city of witches and heretics, Giulia is more vulnerable than ever. How far is she willing to go to continue her mother's legacy?

Weaving together the stories of the women Giulia helped, the men she killed, and those who wanted her dead, this is a tale of magic, secrets, vengeance, and sin in the back streets of Rome--and, ultimately, a fight for power.