Dong Jo (Moon Jung Woong) wakes up after a drunken night out and finds himself in the subway. He wrote a novel about Milwol Island, a place where people disappear, and that novel recently won a literary prize. Dong Jo celebrated the literary prize by going out with friends last night and drinking together. After drinking together, he head to his hometown of Incheon. Now, Dong Jo finds that his bag is missing. He goes to the subway lost & found center. There, Dong Jo finds his red backpack, which he lost back in his high school days. Dong Jo's past starts flashing through his mind. He begins to find his friends one by one. There is one friend named Ki Jung (Shin Jae Seung), who told Dong Jo about a mysterious world that formed the basis of Dong Jo's prize winning novel. Dong Jo wants to meet Ki Jung again...