A stranger named Jun-woo approaches Jung-yoon and suddenly says that he saw her future of being stabbed to death in 6 hours on her 30th birthday. She doubts his words but soon follows him to find out the murderer to avoid death. However, as they go deeper into the case, she realizes Jun-woo was the key to recent serial killings. Now she is left with the question of whether he is the savior of her life or the devil trying to set her up.