The NCI team realized that the suspect they arrested was not the real murderer. Ki Hyung goes to an ex-profiler who became a murderer after the Reaper had murdered his family. While conducting a personal investigation of the Nadeul River murder case, Hyun Jun realizes that Sun Woo was the first witness who found Ji Eun’s body. Meanwhile, the Reaper has returned to attack not only Ki Hyung but the rest of the team.