Around 420 B.C. Socrates was named the "wisest man alive" by the Oracle of Delphi. This deeply confused and concerned Socrates because he did not consider himself wise. Instead he thought he was completely lacking in knowledge and wisdom.
So Socrates began to wander Athens in search for men of wisdom. What he found shocked him. Everyone who claimed to be wise could be easily exposed as self-contradictory charlatans and con men. Many of these exposed charlatans were rich, powerful, and well-connected people. It was then Socrates realized the reason he was called "wisest" is because he knew one thing... that he knew nothing. The others did not even know that. Thus he was indeed the wisest.
Socrates probably should have stopped there, but he didn't. Young people began to follow along on these public humiliation tours. Eventually Socrates was jailed and sentenced to death by the The Council of Elders for "corrupting the youth" and making "the weaker argument defeat the stronger one".
This book chronicles Socrates' last few days on Earth. I think it's fair to say that many positive aspects of Western Civilization begin (and probably end) with this book and the numerous related dialogs written by Socrates most famous pupil, Plato.