Amazon: http://amzn.to/2fYSH7K 
Life is cheap on Earth. Overpopulation and fear of attack have forced the population down into subterranean megacities. Elijah Baile and R. Daneel Olivaw (R for Robot) are dispatched to solve the murder of a ‘Spacer’, a person not from Earth, but one the pampered, Elite, K-Selected humans who moved beyond the Solar System with their legions of Robot man servants. Like Monty Python’s British officers, Spacers shouldn’t die. It is simply politically unacceptable.
Continuing the run of Asimov, this is another of his Science Fiction classics, ostensibly a story of robots and spaceships, but with a payload of prejudice and privilege tucked inside.