I read How The World Works by Chomsky - it's a collection of his radio appearances and whatnot transcribed, so it's all nice n colloquial. I'm thinking Bullshit Jobs next, because apparently it's quite funny and easy to radicalize libs with, which to me at the moment feels more useful than dumping communist theory onto someone that'll write it off instantly because gommulism is when no iphone.
Assata isn't theory, but it's educational in the same way and is a very compelling read.