Su-ji finds trouble when a classmate reaches a breaking point on parent visitation day. Ha-rin sends a warning when Su-ji loses Ha-rin's vote. Su-ji's plans gradually fall apart thanks to a friend's betrayal. The 15th game brings an unexpected twist.

Su-ji is trapped by Ha-rin's blackmail. She feels bad keeping a secret from Ja-eun. The class goes on a school trip. Tension builds until everything explodes in a game of survival.