In the wake of Caesar's murder, a cauldron of contrary emotions bubble across Rome. Octavian devises a plan to keep his family from fleeing. Vorenus mourns Niobe's death but curses her son Lucius. Pullo and Eirene get married, not knowing what's happened back in Rome.

Cleopatra arrives in Rome to pay her respects to Caesar, and to get her son legitimised. Erastes' death plunges the Aventine Collegium, and Rome's river commerce, into chaos. Octavian wins over the masses by taking out a loan to pay off Caesar's promise to the people.

As Brutus and Cassius struggle to raise money for an army, Mark Antony's designs on Gaul elicit a shocking edict from Cicero to the Senate. Vorenus provokes an all-out gang war in the Collegium, and a duplicitous youth sets in motion a deadly plan hatched by Servilia.

Her treachery exposed by Duro, Servilia finds herself at the mercy of Timon. Having defeated Mark Anthony in a bloody battle, Octavian sends word he's returning to Rome. Encamped with an army of mercenaries in western Turkey, Brutus and Cassius have plans of their own.

Vorenus returns to the Collegium with his rescued daughters and son Lucius. Denied a triumph in Rome, Octavian urges Cicero to embrace his request to be made consul. To gain advantage over Brutus and Cassius' army, two adversaries patch up their differences.

Brutus and Cassius see their military advantage vanish in the wake of Octavian's new alliance with Mark Antony. In Rome, Vorenus receives orders to prune the ranks of Rome's elite. With the future of Rome at stake, the two armies clash on the plains of Philippi.

Octavian, Mark Antony and Lepidus agree to divvy up Rome's territories. Eirene insists Pullo punish Gaia for insubordination but the slave turns the flogging to her advantage. Levi urges Timon to help him kill Herod, who has arrived from Judea with a secret agenda.

Octavian's campaign for a more virtuous society hits hardest in his inner circle. Vorenus' efforts to discover who hijacked the gold en route to the Roman treasury leave a bitter taste of betrayal. Pullo turns his grief about a personal loss into anger at a new enemy.

Rome is facing a dire shortage of grain, forcing Octavian to turn to Mark Antony to get new shipments from Egypt, but Antony refuses his terms. Fleeing Egypt, Posca gives Octavian the means to turn the people against Mark Antony, setting in motion the wheels of war.

After his defeat at Actium, Mark Antony returns to Egypt and settles into a world of debauchery with Cleopatra. Octavian tries to gain access to the palace but Vorenus stays loyal. To save her own life, Cleopatra dupes Mark Antony and Ceasar Octavian triumphs in Rome.