4th Period Mystery (2009)
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.
Director: Sang-yong Lee
![]() |
Yoo Seung-ho as Han Jung-hoon |
![]() |
Kang So-ra as Lee Da-jeong |
![]() |
Sang-geun Jo as Kim Tae-gyoo |
![]() |
Jeong Seok-yong as Kang Gook-man |
![]() |
Jeon Jun-hong as Embassy |
![]() |
Rie Young-zin as Yun Sang-mi |
![]() |
Kim Dong-beom as Do-il |
![]() |
Jo Yun-hei as Hong Ju-hee |
![]() |
Lee Chan-ho as |
![]() |
Im Soo-hyang as |
![]() |
Jung Young-ki as |
![]() |
Park Cheol-min as Crazy |
![]() |
Oh Jin-ha as Student in grade 2 class 5 |
![]() |
Kim Min-su as Virtual Criminal |
| Directing | Sang-yong Lee | Director |
| Sound | Lee Sang-wook | Production Sound Mixer |
| Visual Effects | Kim Byeong-gi | Special Effects Supervisor |
| Writing | Shin Jai-ho | Writer |
| Art | Jeon Jin-won | Production Design |
| Art | Kim Jin-chul | Production Design |
| Editing | Kyung Min-ho | Editor |