Lee Yoon-Sung, Lee Min-Ho, works at the Blue House as part of the National Communication Network Team. A MIT-educated IT ace with razor-sharp skills, he handles complex systems with calm precision. At the Blue House, he meets Kim Na-Na Park Min-Young, a devoted bodyguard who moves through the same corridors, and an unlikely romance begins to bloom despite a clear warning to keep love and duty separate. The budding partnership pulls them into a larger, darker thread—a meticulously planned plan for revenge that promises to test loyalty, risk, and conscience in equal measure. It isn’t just about feelings; it’s about fusing heart with a dangerous mission.
Two seasoned figures—Lee Jin-Pyo Kim Sang-joong and Park Moo-Yul Park Sang-Min—once protected the president. When a violent incident in Myanmar unfolds, triggered by North Korean agents, the South Korean leadership escapes unharmed, but several officials are killed. In response, the pair rallies a small inner circle to undertake a covert operation: cross into North Korea to target the agents responsible. Choi Eung-Chan Cheon Ho-jin pledges a submarine rendezvous for their return, setting the gears of a dangerous mission in motion and pulling in a cast of operatives who will be forced to navigate moral lines they never anticipated.
As the plan unfolds, the five officials who initiated the mission waver and try to bow out, but the operative group presses on. The mission succeeds in its objectives, but the crew must swim to reach a waiting submarine off the coast. A sniper’s fire aboard the vessel eliminates all the soldiers except Lee Jin-Pyo, who miraculously survives and returns to South Korea, driven by duty to his fallen ally Park Moo-Yul. His homecoming marks the beginning of a personal reckoning that will redefine everything he’s built—and the future he wants for the man who will carry his legacy forward.
Back in Seoul, Jin-Pyo acts on a vow made in the shadows: he tears away Moo-Yul’s baby during a moment when the mother is distracted, and disappears with the child to Thailand. There he constructs a clandestine life, raising Lee Yun-Seong and shaping him into an elite operative amid a world of illicit schemes and whispered loyalties. This origin story casts a long shadow, one that will eventually collide with the life he left behind and the revenge he seeks to mete out against those who set the events in motion. A father’s vengeance threads through a second generation, testing the bonds of family and duty.
As a young adult, Lee Yun-Seong, still played by Lee Min-Ho, begins to view the world with a jaded, practiced eye. In a Thai village, he encounters Bae Sik-Joong, whom he helps free from pressure from Thai gang members. Kim Sang-ho portrays the man behind the aid—Bae Sik-Joong—a cook who provides sustenance and a steady presence amid danger. During this encounter, Yun-Seong stumbles upon a photo of a woman named Kim Na-Na, placing it beside his bed as a quiet symbol of a longing he barely understands. The image—the woman his heart recognizes even before they meet again—deepens the mystery and foreshadows a future where past and present will collide in unexpected ways.
