Secret Reunion 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 is forced out of his job 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.

Song Kang-ho is a South Korean actor. Song made his film debut in The Day a Pig Fell into the Well (1996), and came to national prominence with a series of critically acclaimed performances, including No. 3 (1997), Joint Security Area (2000), Sympathy for Mr. Vengeance (2002), Memories of Murder (2003), The Host (2006), Snowpiercer (2013), The Attorney (2013), and A Taxi Driver (2017).