Baekyeon Girls’ High School goes on a school retreat. While practicing diving, someone pushes Ha Rin into the water, and Ja Yeon jumps in to save her. The next day, Class Five plays a survival game using paint guns. The last five standing, Soo Ji, Ja Eun, Jae Hyung, Eun Jung, and Ji Ae are put in danger of ending up in Grade F.
