The veteran detective Seo Do-cheol and his team at Major Crimes, relentless in their pursuit of criminals, join forces with rookie cop Park Sun-woo to track down a serial killer who has plunged the nation into turmoil.

When a seasoned detective discovers evidence of corruption within a powerful conglomerate, he sets out to bring them down. With the help of a brash young detective, he must navigate a dangerous web of deception and violence to protect the innocent.