⇒ Brutus reflects privately that he doesn't hold a personal grudge against Caesar, but believes that Caesar's death is necessary for the well-being of Rome. He worries that if Caesar becomes king, his behaviour might change, and he could misuse his power. Thus, killing Caesar is preventive, based not on his current nature but on what he might become.

⇒ Brutus's servant Lucius delivers a letter thrown in through the window by Casca. Brutus reads it aloud and contemplates its meaning. The letter urges him to take action for Rome's sake, indicating his decision to join the conspirators. Lucius confirms that the next day is the ides of March. Brutus admits he hasn't slept since Cassius initially talked to him about Caesar.

⇒ The conspirators—Cassius, Casca, Decius, Cinna, Metellus Cimber, and Trebonius—enter. Cassius insists they take an oath to solidify their commitment to killing Caesar, but Brutus declines, believing their cause should be motivation enough. They debate involving Cicero; however, Brutus advises against it, stating Cicero wouldn't follow anyone else's lead. The group agrees to exclude Cicero.

⇒ They discuss whether to kill Antony alongside Caesar. Cassius advocates for both deaths to eliminate potential issues with Antony. Brutus disagrees, thinking it would make them seem excessively violent.

⇒ He believes that Antony will lose power after Caesar's death and hopes their dignified approach will portray them as cleansing the state rather than murderers. The decision is made not to kill Antony.

⇒ At three in the morning, the conspirators decide to disband. Cassius worries that Caesar, who he believes is superstitious, might not come to the capital due to strange omens. Decius claims he can convince Caesar otherwise. Cassius insists they all meet at eight in the morning to ensure Caesar's presence.

⇒ After the conspirators leave, Portia, Brutus's wife, arrives. Brutus is surprised she's awake at this hour. Portia senses his turmoil and asks him to confide in her. Brutus claims he's unwell, but Portia sees through his facade. She assures him of her strength to bear the truth and promises to keep it secret.

⇒ Touched by her concern, Brutus sends her away when there's a knock at the door. Caius Ligarius appears, willing to join the conspirators despite being ill.