During the beginning of the first scene in act one, the townsfolk gather around on the streets in order to greet Caesar. Flavious and Marullus, both are not in favor of having Caesar as the center of attention. They are trying to tell the people that they are being hypocrytical.
Caesar has arrived. During his arrival, Cassius decides to talk to Brutus. Throughout their conversation, Cassius tries to convince Brutus, that both Caesar and him are equals. He is trying to get Brutus to repel againt Caesar.
During the end of this scene, Cassius and Casca find out that Caesar is going to be crowned king. Both Cinna and Cassius decide to throw, the letters that Cassius forged from the people, into Brutus's house. They are trying to convince Brutus into going against Caesar, by motivating him with the fake letters.