In a dystopian, crime-ridden Detroit, the megacorporation Omni Consumer Products (OCP) has taken control of the city's struggling police department, with plans to replace it with a privatized law enforcement system. As a part of their vision for a new city, dubbed "Delta City," they aim to field a robotic police officer that will be more effective than the human force. The first experiment, however, a fully automated droid called ED-209, malfunctions dramatically, leading to the development of a new project that requires a human touch.

Murphy, a dedicated and honest new transfer to the Detroit Police Department, is brutally killed in the line of duty by a vicious gang led by the notorious criminal Boddicker. OCP seizes this opportunity to use Murphy's body for their cyborg experiment, leading to the creation of a part-man, part-machine law-enforcer. Stripped of his previous identity and memories, he is programmed with prime directives that include serving the public trust, protecting the innocent, and upholding the law. As he patrols the streets, his human side begins to resurface, which sparks an internal struggle between his programming and fragmented memories of his past life, including flashbacks of his family and his own brutal demise.