The two identical twin brothers Youngmin and Kwangmin may look the same but were always unlike in characters. When they were teens, Youngmin was a bright and popular kid, but went to jail because of Kwangmin to protect his brother. Since then, his life has changed completely. Meanwhile, Kwangmin always felt inferior to his older brother and his feelings for his brother became more complicated after Youngmin was imprisoned.

Kwangmin is now the chief detective of a police investigation team for drug investigations, while Youngmin works as a delivery man. A cospiracy is implemented by the city's biggest underground drug lord Song Jiseok (fictional character) and the twin brothers have to change positions. Youngmin now acts as Kwangmin in the police department. Kwangmin is shocked that his brother stole his identity and begins to take actions to get his identity back. Meanwhile, Song Jiseok proposes a deal with Youngmin.