Upon arriving on Aurora, Elijah Baley knows that he is facing his most perilous mission. He must find out who killed Jander Panell, the most sophisticated positronic robot ever created, a creature reaching an unprecedented level of “humanity”. However, the only being capable of committing such a crime is none other than its own designer, Dr. Fastolfe. Fortunately for Baley, R. Daneel Olivaw, now the only humaniform robot still in activity, returns to service to assist him.