When the Duke of Milan is brutally murdered, the Assassin Giovanni Auditore is dispatched to investigate. What he uncovers implicates Italy's most powerful families reaching all the way back to the Vatican itself. As Giovanni draws closer to the truth, he becomes hunted himself. He must expose the conspirators before he joins their ever-growing list of victims.

A by-the-book police officer is assigned to secretly investigate a team leader who believes that the rules shouldn't stop an investigation. As the officer investigates further, his own attitudes begin to mirror the team leader's.