Lim Kang carries the weight of two worlds on his shoulders, balancing the mundane life of a high school student with the bone-shattering duty of a secret vigilante known as the "White Cap." While his classmates fret over exams and social circles, Kang stalks the shadows of South Korea to intercept the Xenoterrans monstrous, otherworldly invaders that have plunged humanity into a desperate fight for survival. His life as a hidden protector is disrupted when the scale of the invasion explodes globally, revealing that these creatures are far more organized and intelligent than simple beasts. The emergence of other superhumans across the planet complicates his mission, as he finds himself navigating a treacherous landscape of shifting alliances and mysterious "Scents" that define a hero’s unique power.

Internal pressure mounts as Kang realizes that the monsters have identified him as their greatest threat, strategically orchestrating disasters to isolate him and stunt his burgeoning potential. This chilling shift in enemy tactics forces him to confront the terrifying reality that his raw strength may not be enough to save everyone, especially as sinister forces within the superhuman ranks begin to reveal their own dark agendas. Despite the encroaching darkness and the crushing isolation of his double life, Kang refuses to falter or retreat into the safety of anonymity. Driven by an ironclad resolve to end the monstrous occupation, he pushes his limits to transcend his own humanity, determined to stand as the ultimate shield for a world teetering on the brink of extinction.