Detectives In 40 Minutes Aka 4th Period Mystery (2009)
Aka: 4Gyosi Churi Yeongyeok, Detectives In 40 Minutes, 4th Period Murder Mystery
Directed: Lee Sang-yong
Genre: Thriller, Mistery
Country: South Korea
Cast: Yoo Seung-ho, Kang So-ra, Jo Sang-geun, Jeon Joon-hong, Jeong Seok-yong, Park Cheol-min
During fourth period, high schooler Da-jeong finds his 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.