A high school girl, Yu Shan, has long harbored a crush on her classmate, Pin Lun. She finds satisfaction in stealing his small belongings, as this gives her a sense of possession. She knows Pin Lun's weekly schedule, including when he practices piano. Once, Yu Shan sneaked into the music classroom ahead of time, and reveled in the pleasure of accompanying Pin Lun from a close distance as he played the piano.

After his suicide, a teen ghost contacts his classmate through sign language, revealing the queer love and pain they were never allowed to voice.

After the final exams, a body is found hanging in the men's bathroom, its cause of death uncertain—suicide or murder? With no clear signs of foul play, the investigation uncovers bullying within the class and complex student dynamics. The suspects include a trusted teacher, a class president fighting for justice, a passive gifted student, a weak follower, and a powerful troublemaker. As motives and opportunities are questioned, the mystery of who killed the student unfolds in the near-empty school.