One day, Jin Yi-soo loses his father, his only family, in a surprise attack by unknown assailants. However, as time passes, he begins to realize that his father was no ordinary man.

Just as his life is threatened by another attack, people claiming to be his father's former colleagues appear. Through them, Jin Yi-soo encounters the assailants' true identity: Cheongdo Corporation.

Cheongdo's goal is to expand and redevelop the corporate city through illegal means, mobilizing its organizations and agents, ultimately securing political influence. Learning that his father and his father's former colleagues were secret agents resisting the Cheongdo system and violence, Yi-soo joins them.