Caesar, now dictator following civil war, plans to attack the Parthians, leaving Dolabella and Mark Antony as consuls. During their first meeting, Caesar is assassinated. The assassins, including Decimus, Brutus and Cassius, instigate riots on the streets of Rome and General Lepidus, Caesar’s military officer, brings in soldiers.
Antony agrees to work with Caesar’s killers to achieve peace, with the condition that Caesar be given a state funeral, during which his fortune is left to his adopted son, Octavian.
There are riots on the streets once more. Octavian visits Cicero who advises him to go to Rome to win the support of the people. While Octavian confronts Antony, Cicero is summoned to talk to Brutus, Cassius, and Decimus. On hearing that opposition to Antony is growing, Cicero returns to Rome to launch an attack leading Antony to withdraw from Rome, with an army. Civil war seems inevitable.
Cicero travels north to meet Octavian and agrees to make the Senate legalise their army if Octavian will fight alongside Decimus, against Antony. Antony marches north and besieges Decimus in Mutina.
Eventually, Cicero gets Octavian his imperium (power to command), but fails to have Antony declared a public enemy. Fulvia, Antony’s wife, gets the Senate to send envoys to Antony, offering peace.
Antony prepares for battle. The peace mission fails, the Senate declares war on Antony, and two armies, commanded by Hirtius and Pansa, set out to join Octavian and relieve Mutina.
One army is ambushed by Antony, but Octavian and his companion, Agrippa, crush Antony’s forces outside the walls of Mutina. Antony flees with a handful of his men. When Octavian marches his victorious army to Rome, demanding to be made Consul, Cicero realises Caesar’s heir is a greater danger to the rule of law than his adoptive father ever was.