North Korean detective Lim Cheol-ryung (Hyun Bin) lost his wife and unit when his superior Cpt. Cha (Kim Joo-hyuk) betrayed him in order to steal engraving plates that print U.S. counterfeit bills. He joins a delegation to South Korea after learning that Cha has defected there. South Korean detective Kang (Yoo Hae-jin) is assigned to the covert joint investigation in order to find Cha, but he’s only told that Cha is a simple murderer and nothing more. The South Korean Intelligence Agency believes that there is an ulterior motive behind finding Cha and asks Kang to interfere with the investigation until they can find out what’s really going on.