A troubled teen hears an eerie sound from an abandoned spot inside her high school, to which a former student has just returned as vice principal. Kim Seo-hyung, Kim Hyeon-soo, Choi Ri, Seo Hye-won, Kim Hyung-seo, Park Se-hyun, Lee Ji-won, Kim Seong-nyeo, Zang Won-hyoung, Kwon Hae-hyo, Lee Joo-shil Added on Netflix 2021-09-09. Youtube Trailer