Yoo Jin-woo, an ambitious CEO of an investment firm specializing in optical devices, travels to Granada, Spain, after receiving a cryptic phone call from a young game developer named Jung Se-joo about a groundbreaking augmented reality (AR) video game. Upon arrival, Jin-woo discovers that Se-joo has mysteriously vanished, and the game—controlled by Se-joo's code—has a dangerous glitch that blurs the lines between the virtual world and reality. As Jin-woo becomes deeply entangled in the game's immersive battles, he meets Se-joo's older sister, Jung Hee-joo, the pragmatic owner of the rundown hostel where he stays. Together, they must navigate a maze of corporate betrayal, supernatural phenomena, and life-threatening consequences to uncover the truth behind Se-joo's disappearance.