Lee Yeo Reum gets dumped by her boyfriend and, soon after, her mother dies in an accident. She goes through one of her worst moments in her life. Lee Yeo Reum then makes the decision to live a complete different life from before and not do anything. She quits her job and moves to a small village, where everything is strange to her. There, she meets the residents, including An Dae Beom, and gets to know them. An Dae Beom works as a librarian. He hardly talks to people, but, when he does, he talks with a stutter. Somehow he gets comfortable and happy being with Lee Yeo Reum. Throughout this time, Lee Yeo Reum also discovers who she really is.

On the day the 15-year statute of limitations expired on a high profile serial murder case that claimed the lives of 10 women, a family member of the victim throws himself off the building in front of Choi Hyeong-goo, the detective in charge of the case. Two years later, a man called Lee Doo-seok publishes a book titled "I am the Murderer" claiming responsibility for the murders that took place 17 years ago. His book becomes a bestseller because of the author’s charming looks and his vivid depiction of the crime. The detective and the self-proclaimed murderer meet face to face on a television debate show. Believing that Lee is nothing but a con artist, Detective Choi renews his search for the ultimate truth. Then another man appears suddenly, claiming he is the real killer.