"A plebeian Venus sculpted out of Parian marble ... ", Giulia Tofana plies her illicit trade using her beauty and an ingenious talent inventing the formula for a deadly poison. But dealing with poisons is not so easy and when an imprudent use of her poison occurs, suspicions arise surrounding the deceased, and the witch-hunt begins. Giulia is forced to flee her town, Palermo, assailed by the Spanish viceroy and the plague, and transfers to the Baroque Rome to Pope Urban VIII, where the pomp of festivals alternates with the violence of the executions in the squares. In the city on the Tiber, the beautiful Sicilian clothes herself in the latest fashions, learns to write and with the help of Friar Nicodemo and the connivance of nobles and cardinals, she increases her trafficking in death. Divided by her love for two men, and always swaying between the desire to only follow her instincts and the desire to become a respectable lady, Giulia pursues her dreams, defying the laws of the Holy Inquisition and comes to an unusual ending.