Dirk and MacDuff return to Cambridge to the University that expelled Dirk for cheating more than 20 years ago. They have been employed by Dirk's former professor as security consultants to guard a valuable robot. Within hours of their arrival the robot is stolen and the professor found dead, with Dirk and MacDuff implicated as the chief suspects. The professor was the only person who ever believed in Dirk and he vows to find out who is behind the murder. The chief suspects are Emelda Ransome the brilliant but embittered computer scientist, who has spent the whole of her career developing a fully functioning artificial intelligence, and David Cho, the Chinese programmer who recently arrived from Beijing to help Emelda complete her experiment. MacDuff's girlfriend Susan is also in Cambridge to interview for a new job, and Dirk is concerned that, should she get it, it would mean the end of their London-based detective partnership.