This second episode is based on events that took place in 50 BC and 49 BC. Caesar's proconsulship in Gaul is about to expire, which would mean a loss of the office's immunity against prosecution by his political enemies. He had faced the same situation five years prior, but at that time his command had been extended with the help of his allies Pompey and Marcus Crassus. This time Caesar cannot count on his former allies, as Pompey has openly turned against him, and Crassus was killed in 53 BC. Caesar instead has to rely on Mark Antony for his political maneuvering: newly elected to the office of Tribune of the People (tribunus plebis), Mark Antony has veto power in the Roman Senate.
Meanwhile, Lucius Vorenus, now a first spear centurion (centurio primi pili), and Pullo return to Rome. After dropping off Gaius Octavian, Vorenus returns to his wife, whom he hasn't seen in eight years since he left for Gaul, only to find her holding a fairly new baby in her arms. When Vorenus asks her whose child it is, she tells him it is his grandson by his eldest daughter who has just newly turned 14. Meanwhile, Pullo returns to prostitution and gambling. He's already lost most of his money in a gambling den full of Pompey's supporters when he discovers that he is being cheated by one of his opponents. He stabs the man through the throat, but is injured in the fight that breaks out. Pullo manages to drag himself to Vorenus's home, where he receives trepanation (courtesy of Vorenus) from a Greek doctor.
Caesar's political enemies, led by Pompey, plan to pass a motion in the Senate that would set an ultimatum for Caesar to surrender his command, or be declared a public enemy. Pompey enlists the help of Cato the Younger, Metellus Scipio (Pompey's new father-in-law), and of the reluctant Cicero. Pompey wants the motion to pass by a large majority, so that Caesar would see that he is isolated and has no political supporters. On the other hand, Pompey also expects the motion to be vetoed by Caesar's ally Mark Antony, in which case the blame for any subsequent escalation would rest with Caesar. However, a brawl erupts on the Senate floor and Mark Antony's veto is not recorded, nor is the session formally adjourned. Pompey is taken by surprise, and arranges for the Senate session to be continued the next day so that the tribune's veto can be recorded. He also gives orders to his minions that Mark Antony must not be harmed in any way.
Not knowing of Pompey's orders and feeling threatened because of his association with Caesar, Mark Antony calls on the soldiers from Caesar's 13th Legion (Legio XIII), including Vorenus and Pullo, for protection. With Vorenus and Pullo walking beside him, Mark Antony makes his way to the Forum in order to properly record his veto in the Senate. Just as they are marching through a throng of Pompey's supporters, a friend of the gambler Pullo killed in the gambling den fight lunges from the crowd with a knife and attacks Pullo. Though the assailant is cut down swiftly, both sides believe that Mark Antony was the intended victim and a bloody fight erupts between the two mobs, just as Pompey emerges from the Senate House. Vorenus and Pullo escape with Antony, though the former is wounded and barely survives the return to Caesar's 13th Legion in Cisalpine Gaul (northern Italy).
Upon hearing the news, Caesar marches his army south toward Rome, marking the beginning of the civil war. Caesar crosses the Rubicon River with the remainder of his army in January, 49 BC. As the news is cried throughout the city, Niobe suckles the baby, indicating that it is really hers.