Italy 1492: Pope Alexander VI is elected. And so begins the Borgia reign of terror. Alexander murders, bribes and betrays to establish his dynasty. Every day, the River Tiber is full of new bodies. Sancha de Aragon, daughter of King Alfonso II of Naples, arrives in Rome newly wed to Alexander's youngest son, Jofre. Their marriage protects Naples against the ambitions of the French King Louis and gains Spanish support for the Borgias. But Rome is very different to her beloved Naples. The debauchery of the Borgia inner circle is notorious. Sancha is no innocent however: she possesses an indomitable spirit which allows her to survive in the snakepit.
Lucrezia Borgia's vicious jealousy stings Sancha at first, but gradually the two young women develop a cautious friendship. Lucrezia, adored by her father but used ruthlessly as a political tool, seems deceptively innocent and sympathetic, and their bond strengthens when Lucrezia is married to Sancha's treasured brother, Alfonso. But when Sancha falls in love with Cesare Borgia, her husband's enigmatic older brother, she has no idea of how bizarre and internecine are the family's true ties.