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.

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.

The people of Rome are starving. There have been many grain shortages over the past few months, but things have gotten particularly bad. In hopes of keeping the people from openly rebelling, Octavian sends Atia and Octavia to Alexandria in order to negotiate a deal with Mark Antony, though his real reasons for their trip is soon revealed. Meanwhile, Titus Pullo and Lucius Vorenus must try to keep the peace amongst many of the mercenaries who are in Rome.

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.