Hoyeong Lee’s quiet life is disrupted by an apocalyptic warning, leading him to a mysterious tower where he and others must complete life-threatening missions to survive. With only a secret strategy guide to aid him, Hoyeong navigates each challenge, gaining his companions’ trust. However, his toughest test is Seoyeon Son, a deadly assassin with him in her sights on the ominous “Day of Blood.” As survival becomes a race against time, Hoyeong must decipher Seoyeon’s next move, using every skill and ounce of wit to stay alive.