Taken from Plutarch's history of the Romans, the theme of this tragedy is kingship versus republicanism, power politics, treachery, and the violence that breeds violence after Caesar's murder. It was as relevant to Shakespeare's day as it is to ours. The ghost of Caesar the aspiring king has a major part in this play just as the ghost of Hamlet's father the king affects that play. The Signet Classic Shakespeare edition of this work has excellent notes and explanations.
ACT I: In Rome
The city is full of high rumour and tension. Fearful portents are in the sky, omens in the air, and soothsayers cry doom. Caesar is popular, and may be crowned emperor: Rome's proud history as a republic would end. His jealous enemies plot to terminate him, but they need Brutus' help to make their plot appear more noble and popular, as the people respect Brutus; he cares for democracy and the republic, and only opposes Caesar for Rome's great traditions, not through jealousy.
ACT II: Rome
Tensions rise further, Brutus becomes a chief conspirator. So many are now in on the secret that they may be given away at any second. Caesar is suspicious and may grow too nervous to go out in public. Brutus wisely urges constraint amongst the plotters: they must only 'carve' Caesar and not 'butcher' his supporters, as this would loose them popular support.
ACT III: Rome; before the Capitol
Tensions can rise no higher. Caesar is stabbed to death: seeing his friend Brutus in on the act he utters the famous dying words, "Et tu, Brutè?". To calm the scandalized crowd, the honorable Brutus explains logically that it was done for the good of Roman democracy, that Caesar was a tyrant in the making, and too ambitious. The crowd accepts this. Brutus then makes the tactical error of a lifetime and allows Mark Anthony to address them, who gives the crowd the 'hearts and minds' speech of a lifetime, touching their emotions as well as their logic. He scorns the conspirators with subtlety. He reminds them how much they loved Caesar, and how much he loved the common folk. The murder is an outrage--men of supposed honour killed a good man through their ambition, not only to put down Caesar's. The crowd turns ugly and goes looking for lynch-mob justice.
ACT IV: the war HQ of both sides
Civil war is unleashed. Mark Anthony and Octavius gather an army to match Cassius and Brutus: it was never going to be so simple as to just kill Julius Caesar. And all the omens have not yet finished coming true--Caesar's ghost returns to haunt Brutus in his battle-tent: the worst omen yet.
ACT V: the battlefield
They 'cry havoc, and let slip the dogs of war'. The fog of war descends, and in the confusion of the battle the conspirators think are losing, and they lose hope, although things are not as bad as they seem. In despair they fall on their swords. And so kingship has won and the time of the Caesars has begun.
This synopsis report prepared by Michael JR Jose