Chinese secret agent Da-hee receives intel that a large number of illegal firearms are being smuggled into Korea and is sent to investigate the case. She meets Su-han, who is supposed to help her with the case, but due to his lackluster skills they fight over trivial things. But as their witnesses are suddenly murdered, the two of them quickly become the prime suspects.
A prosecutor is falsely accused of sexual assault in a suicide note from a woman that he is convinced was actually murdered. As he investigates her death to clear his name, he realizes that the truth lies in a huge financial scandal.
While investigating the kidnapping and murder of a little girl, a detective spots a piece of graffiti that depicts the crime scene perfectly—but the graffiti was drawn a month before the crime took place, and that the artist knows more than he is telling.
