A millennium into the future, two advancements have altered the course of human history:  the colonization of the Galaxy and the creation of the positronic brain.  On the beautiful Outer World planet of Solaria, a handful of human colonists lead a hermit-like existence, their every need attended to by their faithful robot servants.  To this strange and provocative planet comes Detective Elijah Baley, sent from the streets of New York with his positronic partner, the robot R.