During the investigations of a drug trafficking app, the Monster Cop Ma Seok-do (Don Lee) and his team discover a connection between the wanted app developer, who was killed in the Philippines, and a massive illegal online gambling organization. Meanwhile, in the Philippines, Baek Chang-gi, a former elite soldier, has been controlling the Korean online illegal gambling market, terrorizing it with kidnap, assault, and murder. His partner, the IT genius CEO, Chang Dong-chul plans an even larger scheme in Korea. To put an end to the escalating threat, Detective Ma expands the operation by proposing an unexpected alliance to Jang, and unfolds the biggest roundup mission to hunt down the criminals, collaborating with the cyber unit and Metro Investigations.