原班人马再度以拳制暴，化身最强扫毒凶器！“怪物刑警”马锡道（马东锡 饰）为抓捕新型毒品罪犯朱成哲（李浚赫 饰）及日本黑帮毒师Ricky（青木崇高 饰），与新团队展开韩国最大跨国毒网扫荡行动。拳头当子弹，韩国警队第一肌肉大叔马锡道，誓死要将毒贩一一KO！

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.

During fourth period, high schooler Da-jeong finds her classmate Tae-gyu dead in a classroom and Jeong-hun standing in front of him with blood on his clothes. In order to stop Jeong-hun from becoming the prime suspect, Da-jeong must help him find the real murderer, who is still inside the school building, under 40 minutes before period four ends.