Florence 1491. Caterina Vespucci, illegitimate daughter of Florence, Lorenzo il Magnifico, is initiated into the secrets of alchemy. When the fanatical monk Savonarola prophesies the apocalypse over Florence, Caterina flees to Rome. She plunges into a passionate affair with Cesare Borgia, the Pope's son. Her red alchemist's cloak and her close relationship with the Borgia's make her known in Rome as a cardinal. But eventually she has to flee from the Borgia intrigues again. At the court of Ludovico il Moro, she desperately searches for the al-iksir, the alchemists' elixir of life, to save her own life.