4th Period Mystery is a 2009 Korean-language Action Crime movie written by Sin Dong-yeop and Shin Jai-ho. The movie is directed by Sang-yong Lee and Lee Sang-yong and produced by Seo Myung-jin under the banner of Sway Entertainment. High school guys must find the killer of their classmate before the next class start, in 40 minutes. 4th period mystery stars Yoo Seung-ho, Kang So-ra, Chi-yong Ahn, In-sook Choi, Jae-sang Han, Soo-hyang Im and Ji-yeong Yoon. The music was composed by Yozoh. Cinematography was done by Moon Ho-jin and editing by Kyung Min-ho. The film has a running time of 86 minutes. It was released on 12th August 2009. The movie made a box office gross of $0 million. Distribution rights for the movie were acquired by Lotte Entertainment.