The narrative turns on three major plot twists: First, Da-hee discovers that China's MSS intentionally assigned her to a suicide mission; because the 500 Tokarevs had been leaked by their own corrupt official, sacrificing an expendable rookie gave China plausible deniability to avoid being accused of sponsoring cross-border contraband. Second, the actual South Korean agent Da-hee was supposed to rendezvous with—Agent Shin Ki-roo ("Mirage")—was struck by a truck on his way to work and spent the entire film comatose in a hospital bed, leaving Soo-han to mistakenly take the gig simply because he shared office desk space. Third, Soo-han is revealed to be a former elite commando from South Korea's 707th Special Mission Group who retired and adopted a bumbling slacker persona to bury his trauma after losing his comrades on a tragic mission.
In the climax, arms kingpin Jeon Hoon kidnaps Da-hee and takes her to a container warehouse. Dropping his clownish front, Soo-han storms the facility using lethal knife combat, improvised weapons, and gunplay, eliminating the mercenary crew, defeating Yuri (Julien Kang), and saving Da-hee. With the arms ring broken, homicide charges against the duo are dropped. In the post-credits, pet-client "Dorothy" is revealed to be an ex-KGB intelligence operative who hid encrypted micro-SD data inside a golden piggy bank given to Soo-han, inadvertently sending the duo off on their next joint mission to Russia.