As Im Cheol-ryung, a seasoned officer from North Korea's special investigation team, bursts into a hidden counterfeit money operation, he is confronted with a shocking betrayal: his superior, Cha Ki-seong, along with his fellow officers, are colluding to steal the master plates used for printing fake currency. This catastrophic revelation leads to a harrowing firefight, resulting in the deaths of Cheol-ryung's wife, Hwa-ryung, and his team, leaving him seriously injured.
In the wake of this brutal treachery, North Korean authorities discover that Ki-seong has fled to South Korea, planning to employ the stolen plates for his malicious schemes. With urgency, Cheol-ryung is dispatched on a mission to track down Ki-seong and recover the plates within a tight three-day deadline. Meanwhile, the South Korean police view Ki-seong as a dangerous killer, assigning Detective Kang Jin-tae, a seasoned investigator from Seoul, to monitor Cheol-ryung, suspecting that he harbors vengeful intentions against the man who shattered his life.
Upon arriving at the airport, Jin-tae intercepts Cheol-ryung, and the two men join forces to investigate one of Ki-seong's associates, Park Myung-ho, in the bustling heart of Myeong-Dong. However, Cheol-ryung, always alert, quickly discerns Jin-tae's true motives and makes a daring escape. Their pursuit intensifies in Jongro, where Jin-tae conducts a tense interrogation on Park, only for him to slip away during the chaos.
As the stakes rise, Cheol-ryung becomes increasingly aware of Jin-tae's surveillance, taking matters into his own hands by removing the tracking device from his phone—an act that leaves Jin-tae blissfully unaware. In their investigations, the duo discovers a shared adversary in Park, who is secretly dealing drugs. A fierce skirmish breaks out, during which Cheol-ryung cleverly obtains one of the assailant's phones to pass to Jin-tae. However, Cheol-ryung has covertly bugged his own phone to track Park's movements, showcasing his resourcefulness.
The unexpected pair soon encounters a local restaurant, where they stumble upon Park's covert meeting with a lieutenant loyal to Ki-seong—who had been present during the tragic warehouse incident. The lieutenant discusses his intent to settle in South Korea, only to meet a grim fate at Ki-seong's command. Cheol-ryung arrives just in time to warn Ki-seong of his imminent demise, leading to an explosive confrontation with the lieutenant. After a thorough search of Park's belongings, the officials finally grasp the full extent of Cheol-ryung's mission.
As the story progresses, Jin-tae's compassionate side is awakened by revelations surrounding Cheol-ryung's dark past, compelling him to extend his support. This burgeoning friendship leads them to the location of Ki-seong's covert deal involving the coveted plates. Tragically, they arrive amid a bloodbath, as Ki-seong ruthlessly eliminates the buyer and his henchmen. Cheol-ryung's quick intervention prevents Jin-tae from acting too hastily, allowing Ki-seong to escape with the precious plates. This moment leaves Jin-tae contemplating the implications of their actions.
The tension escalates further when Ki-seong, desperate and ruthless, resorts to kidnapping Jin-tae’s loved ones, demanding the return of the stolen plates for their safe return. Frightened, Jin-tae confides in Cheol-ryung about his family's peril, who then takes the lead in managing the crisis. Together, they deliver the master plates to Ki-seong, facilitating his disappearance into the night while ensuring Jin-tae's family is freed. Reunited, Jin-tae experiences a profound relief.
However, the peace is temporary, as an epic confrontation between Cheol-ryung and Jin-tae on one side, against Ki-seong on the other, looms large. The clashes intensify, culminating in a hard-fought victory for the duo as they ultimately dispatch the merciless Ki-seong. A year later, the bond between Cheol-ryung and Jin-tae strengthens, shaped by their shared perilous journey, promising more adventures ahead.
