An undercover cop named Ja-sung has spent eight grueling years infiltrating Goldmoon, South Korea's largest crime syndicate. Despite the immense personal sacrifice and moral conflicts, Ja-sung rises through the ranks to become a trusted lieutenant. With the sudden death of the syndicate's leader, a power struggle ensues, putting Ja-sung in a precarious position. His handler, Chief Kang, sees this as an opportunity to destabilize Goldmoon and urges Ja-sung to further manipulate the situation from within. Tensions escalate as Ja-sung wrestles with his dual identities and the increasing suspicion from both sides of the law.

As the internal battle rages, Ja-sung must navigate deadly alliances and rivalries among Goldmoon's top lieutenants, Jung Chung and Lee Joong-gu. Each has their own aspirations for leadership and views Ja-sung as both a pawn and a threat to their ambitions. As the intricate web of deceit grows, Ja-sung's loyalty is stretched to its breaking point. Conflicted and cornered, he faces a harrowing decision that could determine not just his fate but the future of Goldmoon itself.