'Monster Cop' Ma Seok-do investigates an illegal online gambling business led by a former STS Baek and an IT genius CEO Chang. Ma proposes an unexpected alliance to Jang and begins hunting down the criminals.

Detective Ma Seok-do changes his affiliation from the Geumcheon Police Station to the Metropolitan Investigation Team, in order to eradicate Japanese gangsters who enter Korea to commit heinous crimes.

The 'Beast Cop' Ma Seok-do heads to a foreign country to extradite a suspect, but soon after his arrival, he discovers additional murder cases and hears about a vicious killer who has been committing crimes against tourists for several years.

In Chinatown, law and order is turned upside down when a trio of feral Chinese gangsters arrive, start terrorizing civilians, and usurping territory. The beleaguered local gangsters team up with the police, lead by the badass loose cannon Ma Seok-do, to bring them down. Based on a true story.