In the future, whites have become a minority and are treated as second-class citizens by the colored majority. Whites are discriminated against, relegated to shantytowns and allowed to do only menial labor under segregation laws that are beginning to amount to little more than slavery. As conditions grow worse, white 'volunteers' are worked to death in mine pits and the tar sands, where conditions are so brutal that serving as test subjects on alien planets begins to sound better than anything on earth, no matter what the danger.