This movie begins in a flashback. A young woman sees her policeman-boyfriend turn into a cyborg and disappears. Fast forward to a current-day modern city. The same woman (now more mature) looks at a model of the city along with her boss. Her boss makes a speech to her about how much he loves the city and plans to make it bigger, safer and richer. As the young lady leaves, she approaches a man who wants to see her boss. This man's gun is seen within his jacket by the woman and she instantly suspects him to be a policeman. He denies it, of course. The woman leaves the building.

The suspecting policeman enters the office of the woman's boss and starts asking questions about the whereabouts of an employee, a scientist who recently turned up missing. The boss proclaims that he has so many employees and can't keep up with all of them. An argument ensues and the boss's junior man makes a call security to have the suspecting policeman thrown out.

The suspecting policeman also leaves the building and catches up with boss's secretary who is trying to catch a taxi. The man asks the woman to ride with him instead. The two have small talk and the man invited the woman to take her out to dinner. She agrees. They end up at a cozy restaurant, rather than the more snobbish one up the street. The suspecting policeman tells the woman that he's actually a private eye hired to find the missing scientist. She says she knows nothing about him. They end their dinner, the private eye takes her home and leaves; however, a shady man enters the woman's apartment building. The private eye goes back to the woman's apartment to find her muscled by the shady man a threatened by a knife attached to his arm. The private eye fights the man, both of them are thrown out of high story window and the private eye and woman are taken to the hospital.

The woman has only minor injuries, however, the private eye dies. The chief of police is told by a leading scientist that he's going to transform the private eye into the 8 man, a cyborg crime fighter with a human brain. Once he's transformed, his first mission is to fight against a group of cyber junkies, a group of thugs who remove part of their own limbs to replace them with automatic weapons.

The head leader of this gang is a former cop from the private eye's past. The boss of the head leader is a high-tech crime boss who happens to be woman's boss. He's a boss of a pharmaceutical company by day and Mr. Halloween, a man who makes designer drugs and collect cyborgs as toys, at night.

Unfortunately, the cyber junkies go berserk and it's up to the robot cop or the 8 Man to bring them to justice. After that, the private eye and former cop finally meet. The former cop talks about their past to the secretary, who is held hostage. He tells her the story about how he and some other dirty cops secretly kept drug money for themselves. When the private eye named Hazama, who was also a cop back then, found out about it, he threaten to turn them in. Unfortunately, the former cop, named Tony took Hazama's sister as a hostage and killed her in front of Hazama's eyes.

Back to the present, Hazama reveals himself to Tony and the secretary, who is in love with Hazama as the 8 Man. Battle breaks out between Tony and Hazama; Tony is killed; and the woman is rescued. Hazama decides to take a boy, who was unfortunately orphaned under his wing and start his own Detective agency. The woman now works for Hazama as his receptionist.