The Blood of the Bull. Memoirs of the Borgia Sibyl, #3

Rome 1494: Giulia Farnese has risen to heights of power and influence as mistress to Pope Alexander VI, her beloved Rodrigo, but storms loom on the horizon. A French army is marching toward the Kingdom of Naples, and all that stands in their way are the fragile Papal States.  If Rodrigo won't surrender to the French, he has enemies who are eager to see him deposed - even if that means the French sack the city of Rome and kill thousands.
Yet an even darker threat is growing. In Florence Friar Savonarola's movement is burning books and priceless works of art, determined to purify society and destroy the Renaissance itself. Giulia's own abilities as a seer make her a target for Savonarola's purifying zeal. The repentant concubine of a Borgia Pope would be the perfect tool to bring Pope Alexander VI to his knees. In a web of deceit, assassination and betrayal, Giulia must face her most dangerous enemies without Rodrigo by her side.
To prevail, she will need all her wits and courage to descend into the darkness of the underworld - and return if she can.