During fourth period, high schooler Da-jeong finds her classmate Tae-gyu dead in a classroom and Jeong-hun standing in front of him with blood on his clothes. In order to stop Jeong-hun from becoming the prime suspect, Da-jeong must help him find the real murderer, who is still inside the school building, under 40 minutes before period four ends.
Cast
Yoo Seung-ho
Han Jung-hoon
Kang So-ra
Lee Da-jeong
Sang-geun Jo
Kim Tae-gyoo
Jeong Seok-yong
Kang Gook-man
Jeon Jun-hong
Embassy
Lee Yeong-jin
Yun Sang-mi
Kim Dong-beom
Do-il
Jo Yun-hei
Hong Ju-hee
Lee Chan-ho
Unknown
Im Soo-hyang
Unknown
Jung Young-ki
Unknown
Park Cheol-min
Crazy
Oh Jin-ha
Student in grade 2 class 5
Kim Min-su
Virtual Criminal
