A rising tyrant is reveling in his own power. Another man is determined to stop him. The result changes the course of history.
"Et tu, Brute?" -- Caesar
"If then, that friend demand why Brutus rose against Caesar, this is my answer: not that I loved Caesar less, but that I loved Rome more." --Brutus
And here's the jist: The Roman Republic is enjoying a wonderful time of peace: Pax Romana. Julius Caesar is swathed by plebians who are on their knees, begging him to take the throne. He seems like the perfect ruler, in the most perfect nation, in the most perfect time. Only those closest to him know his true hunger for power, and coupled with their want of personal gain, they prepare to murder him. As Caesar marches up to the courthouse that fateful afternoon, a soothsayer calls out, "Beware the Ides of March!" Translation: Beware the thirteenth of March. Caesar laughs it off, and continues on his way. Once he take his place at the courthouse, his friends surround him. Without much hesitation, they stab him multiple times. Caesar struggles, but once he sees his closest friend, Brutus, also stabbing him, he gives up. The Roman Republic descends into chaos. Brutus and the rest of the conspirators flee into Asia Minor. The Second Triumvirate (Octavius, Lepidus, and Antony) pursue them and push them into battle. Rather than let death meet him, Brutus embraces death courageously and commits suicide.
Brutus alone did what he did for the greater good.