For a three-act plot analysis, put on your screenwriter’s hat. Moviemakers know the formula well: at the end of Act One, the main character is drawn in completely to a conflict. During Act Two, she is farthest away from her goals. At the end of Act Three, the story is resolved.
Act I
Griffin comes up with the best idea ever: to go undercover as a black guy and find out the truth about racism. After he darkens his skin and heads into the heart of Dixie, there's no turning back.
Act II
Being black is not as fun as Griffin thought it would be. In fact, it really sucks. And it seems to be getting worse the longer he stays undercover. It gets to the point where Griffin cannot deal with it. He's approaching breakdown territory.
Act III
You didn't think there wouldn't be consequences to a white guy pretending to be black, did you? Griffin becomes a TV star because of all the interviews that he's giving about his work, but at the same time his town hates him. They threaten to castrate him, and his family moves to Mexico to get away from the threats. The book ends with Griffin imagining a violent and depressing future for blacks and whites.