Two ex-lovers navigate their lives post-breakup — struggling to redefine their relationship, from partners to strangers and everything in between.

The high school senior girls discovered a 'Ghost Hide and Seek' tape recorded by their seniors in the broadcasting club. Through the tape, the girls learned about a rumor that if they win in the ghost hide and seek game on the upcoming school anniversary, they can receive a perfect score on the college entrance exam. The girls decided to recruit Min-joo, a second year student from the religious club, as a mercenary and made a decision to participate together in the ghost hide and seek.

Student teacher Kang Eun-kyung encounters a group of girls in a black magic club who are topping the national mock exams.