In Act One, Caesar is not even present yet his deeds and ego go before him. He has led Rome "in triumph over Pompey's blood." The people ("the common herd") of Rome are pleased but other nobles are becoming increasingly concerned about Caesar's seemingly insatiable ambition.
Act Two finds the consipirators (among them Cassius, Casca and Cinna) worried because Caesar has requested a prophecy from the augurs and his wife, Calpurnia, has a dream in which she sees her husband's statue running with blood and the Romans bathing in it. It is not taken lightly by the conspirators. Although Caesar is warned by the soothsayer to "beware the Ides of March," his ego causes him to disregard both the soothersayer's and Calpurnia's warnings.
Casear is betrayed by those he thinks closest to him, including Brutus, who stabs him along with the others. "Et tu, Brutus?" he cries. (You, too, Brutus?)
Though Casear is dead, he remains powerful. In Act Four, his ghost comes to Brutus' tent to tell him they will meet again at Phillipi.
By Act Five, things have gone badly for the usurpers and Caesar's power is still felt. The dying Cassius proclaims, "O Julius Caesar, thou art mighty yet! Thy spirit walks abroad, and turns our sword in our own entrails. Brutus, compelled by guilt and regret, committs suicide on his own sword. His last words are "Caesar, now be still."
The conquerers learn in the end that Brutus, "the noblest Roman of them all," did not submit to bondage, but "only overcame himself."