On the night of March 14, 2001, exactly the day after the accident at Yongdu High School, four boys return there to solve haunting mysteries. All people are talking about is that Jung Soo-jin was involved in the death of her classmate, but the girl intends to find out what really happened and regain the trust of her lover Jang Sung-tae. The pair search for clues, but discover a much darker secret hidden within the walls of the school, and a hunt begins for both.