This novel depicts the U.S. with an alternative history: What if there had never been a Civil War and several Southern states still had slaves? Not only are there slaves, many Northerners are openly racist. Any black person can be stopped and asked to show papers proving they are free.
The author does a brilliant job of weaving details about the Constitutional Amendment and federal laws that allow slavery to exist. The treatment of slaves is chilling; for example, a white manager who works for a huge corporate farm describes how well they treat "Negroes" where slaves are worked to exhaustion, forced to work even when they are sick, and all must sing a song about how happy they are to work for the corporation.
Unlike most alternative history novels, one can't leave this book and feel relieved that it's fiction because racism is still all too prevalent in the U.S.