Brutus and Cassius struggle to raise foreign armies to oppose the Cesarean party. Mark Antony's plans to change his post-consul proconsular governorship from Macedonia to Gaul are derailed when Cicero delivers an in-absentia message to the Senate, and throws his support behind Octavian. Vorenus struggles to contain an all-out gang war in the Aventine Collegium, of his own making, that he blames on Pullo. In the house of the Julii, Octavia passes the hours in a drug induced daze, while a duplicitous youth named Duro, planted amongst the Julii by Servilia, looks for the chance to set a deadly plan in motion.

Pullo races to find Vorenus with news of his family's fate. Servilia's plans to eliminate a rival exact a high price from her. Cicero is astonished when Octavian sends word that his victorious legions are coming home to Rome. In Rome, Timon finally grows weary of Atia's bidding.

Despite Pullo's advice, Vorenus and his family return to the Collegium with his family who is reunited, and cleansed of their ordeal. Octavian is denied a triumph and urges Cicero to endorse his bid to be made Consul in exchange for an agreement to allow Cicero to veto his actions. Octavian takes both Cicero and the Senate by surprise with his first Consular act. Vorenus attempts' to make peace with Memmio and Cotta create suspicions that he has gone soft.

Vorenus receives orders to plunge Rome into a bloodbath the likes that have not been seen since the dictatorship of Sulla. Octavia reveals her secret to Atia, and the armies of the Liberators and the Caesarians clash for the last time, with the fate of Republic in the balance.

Antony's nature reasserts itself, and challenges his alliance with Octavian. Timon and Levi set themselves against Herod's plans. Servilia's public displays of grief leave Atia unsettled. Gaia uses Pullo's punishment as a weapon against him. His daughter's sudden interest in business matters arouses Vorenus' suspicions. Posca gets married.

Octavian proclaims a new era of virtue in Rome, a program that his family and subordinates find impossible to obey. Vorenus is sent on a mission after a missing shipment of gold to discover who mysteriously hijacked it on its way to the Roman treasury. Pullo's loss and rage are channeled against Memmio, Omnipor and their henchmen. Octavian pursues Livia as an "appropriate" bride, and issues Mark Antony an ultimatum he knows he can't refuse.

Following his naval defeat at Actium, Marc Antony returns to Egypt, where he and Cleopatra settle into a world of debauchery. Octavian tries to use Pullo as leverage to Vorenus to gain acess to the palace, but Vorenus stays loyal to Antony. Finally, it is Cleopatra who dupes Antony, saving her own life by sacrificing her honor. Ceasar Augustus triumphs in Rome.