Eager to return to Rome after eight years of war, Caesar ends his campaign with a resounding triumph in Gaul. Back in Rome, Caesar's old friend Pompey is counselled by the Senate, who worry about Caesar's growing popularity. Meanwhile, two soldiers are enlisted to find the army's stolen gold standard.
With Caesar advancing on Rome, Pompey orders a retreat and forces his citizens to pick sides. Meanwhile, Timon is forced to do Atia's dirty work and Vorenus cannot understand why no one is resisting while on a scouting mission.
As the balance of power unexpectedly swings towards Pompey, Mark Antony must make a life or death decision whether to remain loyal to Caesar. Vorenus struggles to rescue his relationship with Niobe before he follows Caesar into war.
Shortly after being granted the right to appeal, Bernard Aspen is found dead in the prison washroom. He had been convicted of the murder of teenager Marianne Cale over a decade ago and Bernard's death sends the team back to investigate the original case. But inside the prison no one will talk to them and the team quickly realise that this could be a long haul. With the investigation stalling and unbeknownst to the rest of the team, Janine included, Richard is sent in undercover by DCS Hogg. If his cover is blown Richard could be a dead man walking.
With Caesar lying dead on the senate floor, the deadly battle for control of Rome is set to begin. Brutus and his accomplices come up against the might of a vindictive Mark Antony, but with Octavian declared Caesar's rightful heir, alliances will have to be made in order to prevent all-out war.