Kim Dong-beom

In August 1950, waiting for UN troops to arrive, the South Korean army assembled to protect Nakdong River. Only 71 student-soldiers are left behind to guard the city of Pohang. Now they are on a mission to defend the country from North Korean troops.

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.

Jang Baek-Ho is released from prison after 4 years of incarceration. He wants to open up a noodle restaurant, but he discovers that 5,000 dollars is missing from his bank account. Jang Baek-Ho then tries to find his wife and 3 children. Their secret is revealed.