Plot

Oh Tae Sik, rather, Oh Gyeon Sik, who has been preparing to become a detective while working a different job, is a private establishment security guard who earns 880,000 won in Daechi-dong, Gangnam. Thanks to his dream of becoming a detective, he is like a bulldozer who does not know how to give up. He always watched CSI and Detective Columbo's movies, analyzing their traits and building his dream of becoming a great detective. He manages to pass the written test, but he doesn't meet the hearing baseline and fails. Gyeon Sik wants to be a detective, because his family has wanted a detective for generations. His grandfather was illiterate and his father had problems with sight. Gyeon Sik ends his depressing day with the comfort of his colleague over some drinks. Then one day, coincidence happens and a fugitive on the run gets caught by Gyeon Sik when he throws a bottle of water he just bought at the runner. Gyeon Sik becomes a hero thanks to this. He has only one wish and that is to be a detective. The major who doesn't know about him promises him a spot on the team. However, the detective team, who are just about to get their investigative independence, are worried that Gyeon Sik will cause trouble and they finally come up with an idea!.