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.
- PUAN VER
Künye
- Lee Sang-yongYönetmen
- Shin Jai-hoSenaryo
Yoo Seung-hoHan Jung-hoon
Kang So-raLee Da-jeong- Jo Sang-geunKim Tae-gyoo
- Jeon Jun-hongByeong-soo
Jeong Seok-yongKang Gook-man
Park Cheol-minCrazy