Secret Reunion (; lit. "Sworn Brothers" or "Blood Brothers") is a 2010 South Korean action film directed by Jang Hoon, and one of the highest grossing Korean films of 2010. The story follows Song Kang-ho as Agent Lee Han-gyoo of the National Intelligence Service (NIS) who falls from grace after failing to stop the assassination of a North Korean dissident. The sleeper cell responsible includes relative newcomer Ji-won played by Kang Dong-won, who gets marked as a traitor when the mission goes south. Six years later both men are working different jobs when they bump into each other and quickly form a bond. This is the second film by director Jang Hoon, who completed Rough Cut two years prior. Plot Ji-won is one of numerous North Korean undercover spies living in South Korea as ordinary citizens, until he's called to fulfill his mission: the assassination of Kim Jong-il's second cousin who wrote a book that the North Korean government deems as a great betrayal to the Fatherland. However, one of his fellow spies, Tae-soon, betrays his orders by switching his allegiance to South Korea, and Ji-won mistakenly becomes the target for both countries. Lee Han-gyoo is a dedicated agent of the National Intelligence Service (NIS) who tries to foil the hit. Despite having insider information, he doesn't notify his agency superiors, and only involves his team in the mission. Unable to prevent the assassination, and with the loss of his fellow agents in a gun fight, he becomes the sole scapegoat for the agency and gets discharged. Six years later, Lee is now a private investigator and bounty hunter who locates runaway mail order brides, while Ji-won works in construction. Due to a coincidence, Lee gets saved from a mob by Ji-won; they both recognize each other instantly but keep it to themselves. With an ulterior motive for their previous unfinished business, Han-gyoo talks Ji-won into working for him and sharing living quarters - as Ji-won accepts Han-gyoo's offer in order to spy on him, thinking that Han-gyoo is still an agent. While confronting Tae-soon for betraying their home country, Ji-won learns his true reasons behind it and including his own suspicions about Shadow. Tae-soon also mentions that Han-gyoo had come to visit him to check up on him. Ji-won learns that Lee was actually fired from NIS for not reporting the information to his superiors that could've prevented the