Set in the 1920's, during the Japanese occupation of South Korea, Lee Jung Chool was once a member of the Korean independence movement, but he now works as a police officer for Japan. He receives an order to take down the Korean independence group the Righteous Brotherhood.
Lee Jung Chool introduces himself to art dealer Kim Woo-Jin (Gong Yoo) and pretends to be interested in his Korean artworks. In actuality, Kim Woo-Jin is the regional leader of the Righteous Brotherhood. Both of these men are well aware of each other's true identities and intentions, but get closer to each other seeking out more information.
The Righteous Brotherhood learn there are spies within their group and attempt to clamp down on the moles. Soon, the identities of Righteous Brotherhood members are leaked and they flee to Shanghai, China. Meanwhile, Lee Jung-Chool and Japanese police officer Hashimoto (Um Tae-Goo) lead forces to Shanghai, China. There, members of the Righteous Brotherhood decide to acquire explosive for an attack on the Japanese government in Korea.