In the near future, the giant corporation OCP controls the failing Detroit police force as crime rates are uncontrollable. OCP has plans for abandoning the "old" Detroit and replacing it with the new Delta city. In order to protect their future investment, OCP begins development on a fully autonomous robot law-enforcer, the ED-209 droid, but a private demonstration goes horribly wrong when the large robot malfunctions and kills an employee.
Meanwhile, Officer Murphy is killed by gangsters while investigating their drug ring. In the wake of the disaster with the robot droid at OCP, a young executive Bob Morton promotes a new program which aims to graft a human host into a robotic suit. The higher-ups at OCP agree on the premise that having human aspects incorporated into the robot will help prevent a future disaster similar to what happened with the original droid. This causes anger in executive Dick Jones, who headed the ED-209 project. Immediately after Murphy is pronounced dead, OCP begins grafting him into the RoboCop exoskeleton.
The RoboCop suit is programmed with three prime directives: serve the public trust, protect the innocent and uphold the law. However, OCP also included a secret fourth directive: RoboCop can not directly harm or arrest an OCP executive.
RoboCop proves very successful in his law enforcement capability in Detroit. His success leads Morton to be promoted within OCP, which creates jealousy in Jones. Jones hires a man named Boddicker, the same man who killed Murphy, to murder Morton. RoboCop later traces Boddicker and partially defeats him, whereupon Boddicker mentioned Jones's connection to the murder. RoboCop confronts Jones, who admits his guilt, but RoboCop cannot detain him due to the fourth directive. Jones sets the old ED-209 droid upon RoboCop, who escapes to find the greater part of the Detroit police department against him on orders from Jones.
RoboCop and Officer Lewis, who was Murphy's patrol partner prior to being killed (and who suspects RoboCop is Murphy), escape and head out to find Boddicker. A large battle ensues and RoboCop kills Boddicker and his crew while acquiring their large weapons. They return to OCP headquarters and confront Jones, who is meeting with the OCP president. RoboCop replays his recording of Jones's admission of guilt to the president. Subsequently, Jones takes out a gun and holds the president hostage. Remembering the fourth directive, however, the president verbally fires Jones from OCP allowing RoboCop to shoot and kill him.
Behind the graphic-violence-fused action-film satire of RoboCop is a story with underlying themes exploring how artificial intelligence relates to humanity and how technology allows man to exceed the limits of his body.
In the film, the is a sharp contrast between "hard-AI" (the ED-209 droid) which is fully robotic, and "soft-AI" (RoboCop), which has biological human elements. The ED-209 is depicted as a cold, merciless killing machine which is often incapable of discrimination between criminal and innocent. The droid is shown in the story as having no true human reasoning power, instead relying on simple (and malfunctioning) computer programming. RoboCop, on the other hand, has a significant amount of human reasoning power which has also been augmented by four directives which influence his behavior. In the exposition, RoboCop transitions from the human Murphy to the seemingly unfeeling RoboCop. Later on, RoboCop starts to regain memories of his former self and family, which can be interpreted as RoboCop regaining his humanity after it was stripped away from him. This is partially analogous to the progression of Yod in He, She, and It. Yod starts out cold and mechanical: decidedly non-human. However, Yod has the capacity to learn and therefore gains many human characteristics as his short life progresses.
Murphy's immense cybernetic overhaul allows him to bypass the physical weaknesses of the human body, granting him incredible strength, speed, and endurance. However, the limitations of a machine-based body are apparent as well, and Murphy suffers from mechanical failure when taking damage. Also, the limitations of Murphy's programming show themselves in the form of the dreaded Fourth Directive, which paradoxically hinders his ability to carry out his other programmed tasks. Related to this is the humanity of RoboCop. Unlike many of the characters in the stories we read, RoboCop is nearly entirely a machine now, unlike Lindsay or Molly who have just gone through modifications.