Four years after the events of the Garibong district round-up operation, Geumcheon Police's Major Crimes Unit is given the mission to repatriate a fugitive who fled to Vietnam. Beast cop Ma Seok-do realises that there is something up with their suspect's willingness to turn himself in and subsequently uncover crimes committed by a terrifying killer named Kang Hae-sang. Ma and his unit begin their investigation across two countries and follow the bloody breadcrumbs left behind by Kang.