Detective Yoshioka is investigating the drowning death of a young woman in a red dress. Lying face down in a muddy puddle, her stomach is found to be full of sea water. As the investigation progresses, clues begin to appear that point to him being the murderer - as his fingerprints are found on the body and some of his personal items are found at the murder scene. As more bodies turn up, killed in the same way, even he begins to wonder whether he may be the very murderer that he is pursuing.