Subway Mystery | Dying people... Disappearing people... A cross puzzle of life and death. Kyung Sik, the driver of subway line 2, clashes with his wife over money borrowed by his brother Yoon Sik. Eventually, his wife leaves home, and to make matters worse, his brother also disappears. Kyung Sik suffers extreme stress due to the continuous misfortune. One day, while driving, he discovers the body of a woman who committed suicide. A woman strangely resembling his wife. Meanwhile, the police believe Kyung Sik is involved in the disappearance of his wife and brother and persistently interrogates him...