Yuuto Lenix, a former DEA investigator, was arrested and received a life in prison for the murder of his partner, which he claims he didn't commit and was framed for the murder. While serving his sentence, an FBI agent offers him a deal to look for a particular criminal hiding in the same prison. If he successfully delivers what the FBI is searching for, then Lenix will go home free. He accepts this "under cover" assignment, hoping to be set free.