Four years have passed since mysterious orbs appeared in the skies above South Korea. Though they initially posed no direct harm to humans, their increasing numbers and looming presence instill fear and chaos throughout society. In response, the government offers college entrance exam incentives to high school seniors in exchange for joining a special military training program. Class 2-3 of Sungjin High School voluntarily enlists, expecting a temporary program—but they soon find themselves in real combat.
As they’re thrust into brutal battles against the orbs, the students face staggering loss and the harsh reality of war. Friends fall one by one, and the line between survival and morality begins to blur. One student, obsessed with exam scores, reaches a tragic breaking point.
Despite the horrors, the surviving students press on, culminating in a final confrontation. In the face of devastation, they struggle to hold on to hope, solidarity, and their humanity.