So I'm thinking we would have to wind the clock back to the '70s to '90s. With the contemporary 24 hour news cycle these things would get exposed today. But say 1987, back when pay phones were a dime and there was barely any cable? Yeah it could happen. It needs to be modern enough though that our heroine is absoluty shocked, appalled, and in total disbelief through out that this going down in modern America.
And what's going down? Some crazy, full-on, KKK level racist stuff. Rape and bondage and totally demeaning full spectrum humiliation. Our heroine, let's say Tasha, is from Chicago or New York or something, and so she's been exposed to racism, but she's never been down to see grandma. Until she graduated college with a degree in like African American studies or something. So she's got an idea from books about the plight of black people and the brutish nature of the Deep South, but it's all just academic.
Until she gets pulled over in old cotton country down in Alabama or Mississippi. She was just on her way to see her extended family, was gonna surprise them, had stopped by some civil rights site and got lost. Speeding back to the highway and that's when YOUR CHARACTER gets ahold of her.