16th century Florence, Italy: Allegra Castagno harbors a secret so big that it can ruin her life and her father's reputation. Exceptionally talented, yet banned from the Florentine guilds, she devises a clever ruse in order to secretly ply her beloved craft. In time, the exquisite jewelry designs of "La Castagna" are being praised in noble courts from Venice to Rome. Resentful of the male-dominated society in which she lives, Allegra rejects all suitors in order to maintain her carefully constructed farce—until an embittered man with a tragic past melts her icy heart. Faced with a serious dilemma, she seeks the help of her scandalous friend, Bianca Cappello, lover of the powerful Francesco de' Medici.