Lucrezia finds Paolo dead in the street, but since there was a suicide note and Paolo didn't read or write, she knows it was murder. After figuring out it was Juan's doing, she burns a chandelier to fall on top of him and his lover in bed. He survives, the lover does not.
Meanwhile, King Charles and the Sforzas are coming to battle Rome. Rodrigo tells Cesare to get him cannons, but they don't have the time to make any. Cesare and the mistress apprentice decide to make 100 plaster cannons and hope the King thinks they are real. He does and they retreat at Rome's walls.