"Prequel: An American Fight Against Fascism" tells the story of the American Nazis (some in Congress!) who worked to undermine U.S. unity and purpose before and during WW2, and the small, often unrecognized, regular-people heroes who resisted them.
Although it's about the 1930s and 1940s, It's the best book on *current* events I've read, because many of the things that happened then are happening again now. It's important and relevant and, remarkably, it actually gives me hope that we can prevail again today against the gathering forces of intolerance, cynicism, and greed. Highly recommended.