I am a huge fan of Viet Thanh Nguyen's book The Sympathizer: A Novel (Pulitzer Prize for Fiction).
The story's protagonist is a communist spy that has infiltrated the American-allied South Vietnamese. He tries to navigate treacherous waters by helping his side without letting his employers know about it. He learns a lot about people and the various cultures he encounters.
Though the book explores some very serious themes, Nguyen somehow managed to make the book hilarious. He is an excellent writer with the gift of wit.
The books that really touch me inspire me to learn more. I knew very little about the Vietnam War going into this, but since reading the book I've gone on to read more about it.
I highly recommend The Sympathizer: A Novel (Pulitzer Prize for Fiction) to all.