An undercover police officer investigating a powerful Korean crime ring is torn between his duty to uphold the law, and his loyalty to the criminal who trusts him implicitly in this tense crime thriller. Under the watch of his superior Kang (Choi Min-sik), devoted cop Ja-sung (Lee Jung-jae) embarks on a clandestine mission to infiltrate the powerful "Gold Moon" crime syndicate. Eight years later, he's become part of the organization's inner circle by establishing a powerful bond with Jung Chung (Hwang Jung-min), the group's powerful second-in-command. When the head of the criminal outfit dies suddenly, however, the resulting internal power struggle threatens to destroy the syndicate, and dissolve the investigation. Now, Ja-sung must make a decision that will show where his true loyalties lie, and that could very well cost him his career, if he doesn't pay with his life, first.