Chapter 10 of The Open Society and its Enemies, also titled TOSAIE, is a reward for some of the past labor. Popper is both eloquent and expansive here, clearly describing his vision of the open society, and giving much needed background on Athens in the 5th Century BCE. He introduces a pantheon of heroes of the open society: Protagoras, Democritus, and, above all, Pericles and Socrates.
Given that much of what we know of Socrates comes to us from Plato, it is a little curious that he seems to ultimately be the most fundamental betrayer of Socrates and his philosophic thought. It seems clear that the "Socrates" of The Republic and other late dialogues is so at odds with the Socrates we see in more personal dialogues thought to be early.
Popper tries to analyze this betrayal, and comes up some interesting ideas, including some supposed signs of guilty regret, but I won't pretend to evaluate them. It is his final chapter devoted to Plato, and I have to say that he closes very strongly. It may even give me the courage to go on to Hegel and Marx, unappetising as they seem.