It is the year 2808. Three convicts are recruited as members of the Cyber Police to keep major criminal activity in Oedo (formerly Tokyo) in check. In return, their life sentences will be reduced by a few years for every mission accomplished. However, to ensure that these convicts are doing their job, the police have secured special collars around their necks. If they attempt to remove their collars or fail to meet the time limit of their mission, the collars will self-destruct.

[Source: Anime News Network]