In Tokyo in 1999, from construction sites to people's daily lives, a large robot called Labor can be seen everywhere. Faced with the increasing number of Labor-related crimes, the police department established a special vehicle section 2, equipped with a special robot PatLabor, to handle special matters. Labor has reached the time of renewal, and the computer operating system that serves as the robot's brain has been upgraded to HOS. At this time, a number of robot out-of-control incidents suddenly occurred, and the mobile police team was responsible for investigating the matter. They found that this was caused by a computer virus related to HOS, and the perpetrator had destroyed all the data and his whereabouts were unknown. In Tokyo Bay, the Babylon Project to build a giant offshore ark to solve Tokyo's land problem has reached a critical moment. 45% of the country's Labor robots are gathered there. If these robots lose control, the consequences will be disastrous.