Act 1 opens with Marullus and Flavius who try to stop the Roman citizens from celebrating Caesar's Victory. Caesar receives a message from a soothsayer who tells him to 'Beware the Ides of March'. Towards the end of this act, Cassius indirectly makes Brutus aware of his intentions whilst trying to figure out Brutus' stance on Caesar as the possible King.
The conspirators as well as Brutus are worried about the future of Rome if Caesar becomes King. Cassius wants to kill Caesar out of jealousy while Brutus being the honorable man he is, wants to kill Caesar to prevent oppression in Rome. They meet in Brutus' garden the night before the ides of march to discuss Caesar's assassination.
It is the Ides of March and due to her dreams, Calphurnia tries to persuade Caesar into not going to the capitol. However, he is later persuaded by Decius, a conspirator, to go to the capitol due to his re-interpretation of Calphurnia's dream. Caesar is killed by the conspirators on his way to the capitol with Brutus stabbing him last. Caesar's last words being, "Et tu, Bruté?-Then fall Caesar."
Et tu, Bruté?-Then fall Caesar
Brutus allows for Mark Antony to speak at Caesar's funeral, held at the marketplace, against Cassius' will . Brutus is the first to address the Roman citizens to explain the conspirators' reasons for the assassination and Mark Antony proceeds. Antony's speech raises havoc and begins a riot which results in the conspirators having to flee their homes.
Brutus and Cassius, after overcoming conflict between themselves, go to battle against Mark Antony, Lepidus and Octavius outside of Rome. Brutus receives news of his wife, Portia's suicide. Initially, Cassius and Brutus seem to be winning, but Cassius misinterprets what is taking place on the battle-field and asks his servant to kill him. Brutus finds Cassius and later commits suicide. Antony finds Brutus' body and says that he is 'the noblest Roman of them all' before returning to Rome to celebrate his victory.