'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.

Hae-woong, an assembly member candidate, is taken out of the running because he became a thorn in the side of a local bigwig, Sun-tae. Hounded by loan sharks, due to defaulting a campaign loan, he decides to get his hands dirty. He steals classified government’s information about an urban development plan and obtains the help of a local gang leader, Pil-do, by promising hefty real estate profit. Now Hae-woong re-enters the race and tries to take revenge on Sun-tae. Unbeknownst to him, his messy journey through politics has only just begun.

On the first day of school, Sin-woo hears about the dangerous student council who even the teachers avoid. When he saves a kid from being cheated by them, he becomes known as 'one punch man.' After being expelled from defending a friend from the student council's torment, he is invited to join them, which confuses him.