The story of Act I takes place 25 years later. Simon is still the Doge. He has sent many of his enemies into exile and taken away their property. Count Grimaldi is one of the people who has been exiled. In the Grimaldi castle, Fiesco is calling himself Andrea Grimaldi so that people do not know who he is. He is plotting with Simon’s enemies to overthrow him. He does not know that his granddaughter (Simon’s daughter) is the young lady called Amelia Grimaldi who is living in the castle.