Four years after the sweeping operation in Garibong-dong, Detective Ma Seok-do and Captain Jeon Il-man head to Ho Chi Minh City, Vietnam to extradite a suspect Yoo Jong-hoon. After their arrival, they meet some Koreans living in Vietnam. Ma interrogates Jong-hoon, who reveals that he turned himself in because Lee Jong-du tried to kill him. Ma and Il-man leave for Jong-du's hideout, only to find him dead, where they learn about the duo's involvement with Kang Hae-sang, a vicious killer who has kidnapped and killed Koreans and several tourists, in exchange for money. Kang's one such victim is a wealthy young Korean named Choi Yong-gi.