- Casca reports on the strange, ominous events that took place during Caesar's triumph. He witnessed a crown offered to Caesar three times, which Caesar refused, and he encountered Marullus and Flavius, the tribunes, attempting to suppress a celebration in honor of Caesar.
- Cassius, fueled by his own jealousy and admiration for Caesar, manipulates Brutus into joining a conspiracy against Caesar. He plays on Brutus's patriotism, sense of duty, and love for Rome to convince him that eliminating Caesar is necessary to preserve the republic and prevent Caesar from becoming a dictator.
- Brutus ultimately becomes the driving force behind the assassination plot. Despite his initial reservations and inner turmoil, he lets Cassius's arguments and his own principles persuade him to join the conspiracy. Brutus's decision to join the conspirators sets the stage for the conflict and events that unfold throughout the play.