Veteran detective Sang-gil and beat cop Eun-yeong are in charge of a case that seems to involve a simple act of self-immolation. Sang-gil initially thinks that it was an accident, but dog bite marks discovered on the body lead him to believe that someone had terrorized and murdered the victim. He and Eun-yeong investigate the source of the drugs found in the body and discover the victim had been pimping out young girls. At the same time, another murder involving a wolf-dog crossbreed occurs The two cases are labeled serial killings. With a connection between the victims uncovered, Sang-gil and Eun-yeong track down a potential witness. While questioning her, one of the mysterious dogs strikes out of the blue, killing the witness and stunning the cops.