Isaac Asimov's Robot City : Book 6 : Perihelion

A man without memory, in a city of robots gone wild. At his side, a mysterious woman whose own identity he has reconstructed, and whose memories of him may be true or false. The young man calls himself Derec. In the shattering climax to his quest he discovers the shocking secret of his true identity. Tormented by a nightmarish disease, Derec must face the genius Dr. Avery, and compel him to reveal the truth!