4th Period Mystery
Release date in South Korea : 2009/08/12
Genre : Thriller
Duration : 86min
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.