The key plot of the series is Lorenzo beginning to try to unite some of the main city-states of Italy, in particular Milan and eventually Venice, together to form a stronger alliance for these cities and help their business. However, the Medici lost their papal account and their bank is threatened with insolvency as the Pazzi conspire with the Pope (Pope Paul II and later Pope Sixtus IV) to stop the Medici. The alliance with Milan is broken up with the murder of Duke Sforza of Milan. Without seemingly knowing or at leat not knowing in detail, Pope Sixtus has Cardinal Riario send a deligation to Florence to try to sooth relations with the Medici and resolve the conflict with the Pazzi. This deligation is sent with armed guards who are actually sent to conspire against the Medici. The Pazzi form alliances with some of the powerful families of Florence so they can also take power after killing the Medici. The choice of Easter Sunday was chosen to launch the conspiracy because the Medici will certainly be in the Duomo attending services. The Pazzi appear to show peace and
reconcliation with the Medici but in reality attack the Medici in the Duomo during Easter. Giuliano is killed from behind by Francesco and his collaborators. However, they fail to kill Lorenzo, who is holed up in a small room in the Duomo with his wife and mother. Eventually, the people of Florence rally around the Medici and the conspirators are rounded up in the Signoria, where they tried to complete their conspiracy by taking authority over the city. This fails and the conspirators are captured and hung from the Signoria. Leonardo da Vinci, who was young and in Florence at the time, drew the hanging of one of the conspirators, who was Baroncelli (Figure 2).
[[File:Leonardo da Vinci - Hanging of Bernardo Baroncelli 1479.jpg|thumb|Figure 2. Leonardo's drawing showing one of the conspirators hung.]]