Beautifully written. Twin sisters run away from their home in the South. Both are black, but one goes on to pass as a white woman while the other eventually returns to her hometown. To be honest it initially made me question - if no one can tell the difference, why not pretend to be white when it's convenient? The book takes place in the 50s onwards where there is still segregation and a lot of discrimination e.g. can't get certain jobs.
Obviously an ignorant question, and the book does a good job of showing how the white-passing sister struggles to deal with the effects of hiding her true identity from everyone around her.