This scene is set in a house. Lepidus, Antony, and Octavius (The triumvirate that now rules Rome) are discussing names of those they will execute. Lepidus is sent on an errand by Antony.
While Lepidus is gone, Antony complains that Lepidus is not fit to share power with him and Octavius. Antony says that he is listening to Lepidus' recommendations of who they should kill only to use him as a scapegoat to protect Ocatavius and himself from slander. Octavius suggests he may be useful because he is an experienced soldier. Antony compares Lepidus to his horse, who is also an experienced soldier, but who is easier to control. He notes that they need to train Lepidus to make him easier to control.
The scene ends with Antony and Octavius determining that they need to take action and gain support at the Capitol since Brutus and Cassius are gathering support outside of Rome.
This scene is set at Brutus' army camp. Brutus is present with Lucilius, Lucius, Titinius, Pindarus (Cassius' servant) and some soldiers. Brutus asks Lucilius if Cassius is nearby. Lucilius says he has come with Pindarus and that Cassius is on his way from Sardis. Brutus expresses growing frustration with Cassius.
Cassius arrives and starts to argue with Brutus, but Brutus tells him they need to keep up appearances in front of the soldiers. They leave to speak in privacy in Brutus' tent.
This scene is set inside of Brutus' tent. Cassius and Brutus argue over Cassius taking bribes in Sardis and for not sending gold to Brutus when he needed it for his army. Brutus affirms his honesty and rails against Cassius for tarnishing their honor by taking bribes. Cassius threatens Brutus but Brutus does not back down. Cassius then pulls out a blade and threatens to kill himself over the way Brutus is treating him. Brutus forgives him and convinces Cassius to put his blade away.
They call for wine and Brutus reveals to Cassius that Portia has killed herself. Messala enters and the three men discuss news from Rome, they have received reports of mass executions of senators by Antony and Octavius. Messala also suspects that his wife and many others have been murdered in Rome.
Cassius and Brutus discuss what they should do next. Brutus suggests they move the army to Phillipi, but Cassius prefers waiting in Sardis for Octavius and Antony to come to them. Brutus manages to convince Cassius that moving the army to Philippi is the better tactical decision. Cassius and Brutus promise never to fight each other again and part on good terms.
Brutus has two soldiers, Varro and Claudius, sleep in his tent so that he can send messages if he needs to. He has Lucius play music to help him get to sleep. Lucius soon falls asleep and the ghost of Caesar appears in the tent. The ghost warns Brutus that he will “see me at Philippi.” After the ghost leaves Brutus wakes everyone, but neither they nor the guards outside the tent saw the ghost. He then determines to begin moving the army.