Set in a future Earth (2035 A.D.) where robots are common assistants and workers for their human owners, this is the story of "robotophobic" Chicago Police Detective Del Spooner's (Smith) investigation into the murder of Dr. Alfred Lanning (James Cromwell), who works at U.S. Robotics, in which a robot, Sonny (Tudyk), appears to be implicated, even though that would mean the robot had violated the Three Laws of Robotics, which is apparently impossible. It seems impossible because.. if robots can break those laws, there's nothing to stop them from taking over the world, as humans have grown to become completely dependent upon their robots. Or maybe... they already have? Aiding Spooner in his investigation is a psychologist, Dr. Susan Calvin (Moynahan), who specializes in the psyches of robots.