I don't understand this book. Could you clarify what is going on in the novel? Like, why did George kill Lennie etc. I read this twice, and I still don't understand what is going on... :(

Please give me a short 5 sentence paragraph on what this novel is about. I still don't understand it. I'm confused with a lot of stuff. If you could give me a few minutes of your time, that would be great! :-) :-)