In order to hunt down an international criminal organization hiding in South Korea, North Korean detective Im Cheol-ryeong (Hyun Bin) is involved in a new joint investigation mission. South Korean detective Kang Jin-tae (Yoo Hae-jin) is transferred to the network investigation team due to a mistake during the investigation. In order to return to the wide-area investigation team, Jin-tae volunteers to be Cheol-rye's partner. Min-young (Lim Yoon-ah) rekindles her love for Cheol-rye after meeting him again. However, Cheol-cheol and Jin-tae are suspicious of each other, but they still carry out a very decent search operation. Just when they finally find the hiding place of the criminal organization leader Jang Myeong-jun (Chen Sun-kyu), FBI agent Jack (Daniel Henney) from the United States suddenly appears in front of them. The still poignant South Korean detective; the equally outstanding North Korean detective; the American detective from the FBI, united by their respective goals, will launch an exciting joint investigation.