Isaac Asimov's Robot City Book 3

Beyond Aurora awaits a brave new world of robots... A man without memory, trapped in a city of robots gone wild. At his side, a mysterious woman who claims to know who he is, but who refuses to tell him. Together, they must find an insane cyborg stalking the streets of Robot City, a time bomb indistinguishable from ordinary robots. The young man's name is Derec. The identity of his female companion and the location of the cyborg are just two of the mysteries he must solve within the fantastic confines of a most unlikely metropolis.