Professor Yoo Myeong Woo is a well-known lecturer and public figure who is famous for collecting ancient books. One day, Professor Yoo Myeong Woo announced suddenly that he wanted to retire, both from his job as a lecturer and a performer on TV and radio. Instead, he will open a bookstore called Memory Bookstore to sell the ancient books of his collection. As it turns out, Memory Bookstore is a trap deliberately created to lure a killer nicknamed Hunter who killed his wife and child, and caused his leg to have to be amputated 15 years ago. When the event happened, Professor Yoo Myeong accidentally learned of the Hunter's love for ancient books, so he was sure the Hunter would come to his bookstore. Through a shop that can only be visited after making an appointment, Professor Yoo Myeong Woo meets various potential buyers, four of whom are suspected to be Hunters. The first suspect is a woodworker named Kim Seong Gon who clearly shows his love for books. The second suspect is Jo Se Joon, a Youtuber who doesn't seem to like ancient books and only came to ask him to write a book about the tragedy of 15 years ago. The third suspect is Kim Sae Byeok, who claims to be uninterested in ancient books, and gives an awkward impression and shows suspicious behavior. Last but not least is Oh Hyeong Shik, a figure who looks like a loving father, but actually likes to beat his five or six-year-old son. Then, is the decision right? Is the Hunter indeed hiding behind the mask of one of the increasingly suspicious-looking suspects?