Tae Oh confesses to Maria about his crimes in exchange for her telling him about the 9th murder. He hopes to learn how Gap Dong was able to stop the impulse to kill. Old buried skeletal remains found at a construction site have Mu Yeom thinking about the possibility that Gap Dong didn't disappear but instead changed his MO, and he starts looking into unsolved missing person cases. Maria's memories resurface and Chief Cha steps in to see how much she knows.