I found 'A Fever in the Heartland' a tough read emotionally, but necessary. It's primarily about the 1920s Klan's takeover of Indiana, so the central character isn't a hero—it's D.C. Stephenson, the Grand Dragon. The book frames him as a monstrous, charismatic figure whose corruption shows how hate movements gain power. It also heavily features his friend and later prosecutor, Governor Ed Jackson, and the journalist who helped expose the scandals, William O. Hutchins. The real 'character' the book investigates, though, is the complacent society that let it happen. Makes you think about parallels today, for sure.
Worth noting it's not a character-driven narrative like a novel; you're following historical figures through a meticulously researched lens. Stephenson's eventual downfall after the murder of Madge Oberholtzer is where the key personalities truly collide, showing how the system finally turned on itself.