CHEN Si-yu and his sister, CHEN Yu-fei, lost their income after their father vanished. Balancing high school with part-time work, they also endure threats and harassments from debt collectors. One day, a special task is announced for ten students, including Si-yu and Yu-fei. Summoned to the auditorium, without the teacher, confusion sets in. Attempting to leave, the siblings find the doors locked. Faint sounds fill the air, and shadows envelop the space. A bullied classmate emerges, announcing the “Graduation Challenge.” In a peculiar tone, she congratulates them on the opportunity to change their lives.