As the wars in Gaul come to an end, Caesar is faced with both triumph and tribulation. In Rome, Pompey must balance honour and politics as he's urged to carry out an act of betrayal. Atia of the Julii tries to steer her family between the growing divisions of power.

Anointed People's Tribune by Caesar, Mark Antony returns to Rome with Octavian's liberators, Vorenus and Pullo. After the Senate rebuffs Caesar's compromise for a heroic return to Rome, Antony learns that Pompey has drafted an ultimatum stripping the general of his powe

Caesar is making his way towards Rome, though Vorenus is considering why the army's encountered so little resistance during their patrols. In Rome, Pompey orders a retreat of his forces and assigns his best men to take the city's treasury to their planned destination.

As Pompey 'manoeuvres' outside the city, Caesar seeks to strengthen his hold on Rome. Atia throws Caesar a welcome home party. Pullo delivers Quintus Pompey to Caesar, who in turn returns Quintus to his father with an offer of a truce he knows Pompey will never accept.

Caesar weighs Pompey's counteroffer against Antony's recommendation to chase down Pompey's vulnerable army. Vorenus is forced to reconsider his career choices after a series of business setbacks. A jealous Atia concocts a clever scheme to separate Caesar from Servilia.

Antony is running Rome while Caesar pursues Pompey in the East, but news that the tide has turned, and that Pompey now pursues Caesar, leaves Antony deciding whether to remain loyal or turn against Caesar as Atia and Pompey wish. Atia tries to mend fences with Servilia.

Marooned in the Adriatic Sea, Vorenus and Pullo look to survive. In Greece, Pompey decides to attack Caesar's depleted forces whose lack of options turns into their greatest strength. In Rome, Octavia is enlisted by Atia to ask another favour of Servilia.

Having pursued Pompey into Egypt, Caesar meets Ptolemy XIII who offers the general a surprise gift. Vorenus & Pullo free Ptolemy's incarcerated sister, Cleopatra. Caesar seeks payment from Egypt for past debts and ends up forging a strategic union to ensure his legacy.

With Scipio and Cato defeated, Caesar returns home to a hero's welcome. Vorenus and Pullo's showdown with local thug Erastes gets an unexpected reprieve from Caesar. Servilia's plan to use Octavia to unearth a secret about Caesar backfires.

Proclaimed Emperor by the Senate, Caesar declares the war over. No longer a soldier, Pullo eyes a pastoral future with Eirene; Vorenus runs for municipal magistrate; Octavian retrieves Octavia from her self-imposed exile; Servilia invites Quintus Pompey into her home.

While Pullo descends into Erastes' netherworld, Vorenus negotiates a severance for veteran soldiers on behalf of Ceasar, who invites him and Niobe to one of Atia's parties. Cassius tries to convince Brutus that the life and death of the Republic is indeed in his hands.

Pullo and Vorenus are now heroes to the Roman rank and file, causing Caesar to reward those he would have punished. To the chagrin of the old guard, Caesar decides to add some new faces to the Senate. Servilia conquers the final hurdle in her ambitious revenge scenario.

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.