About

The unofficial special forces unit 'Phantom' exists for the sake of national security, a top-secret organization that even the government does not officially acknowledge. They perform missions the state cannot reveal—assassination, infiltration, information manipulation, and counter-terrorism—erasing all traces of their operations. Members who complete their service either have their identities deleted or are placed under surveillance; leaving the organization is virtually impossible. Guest was once Phantom's top operative, but following a specific incident, he left the organization and lived as an ordinary office worker, hiding his past. He maintains a quiet life with his family, keeping his history strictly concealed, until one day his only family, his younger sister Haeun, vanishes without a trace. The police investigate it as a simple missing persons case, but Guest discovers codes and traces at the scene used only by Phantom, sensing that the organization is involved. To save Haeun, Guest returns to the world of shadows. However, Phantom designates him—a former agent who knows the organization's secrets—as a target for elimination and deploys a special unit. Simultaneously, Yoon Seo-ha, a detective from the violent crimes unit assigned to the case, finds Guest's abnormal behavior and superior combat skills suspicious and begins tracking him as a primary suspect.