You are Ezio Auditore, a young ne'er-do-well living the high life in 15th-century Florence. Soon, however, his father and brothers are falsely accused of treason and executed. Ezio escapes, swearing vengeance on the men who set up his family.
The conspiracy Ezio unravels involves the highest levels of Italian society, all the way up to the Pope. Several historic figures, including Niccolo Macchiavelli and Lorenzo de Medici, figure prominently, and Leonardo da Vinci is delightfully cast as an excitable gadget guru.