Former mercenary Masahiko Yoshida (Akihiko Sai) is a private detective who is grieving over the loss of his lover (Keiko Izumi) a year ago. One day, he receives a request from a young woman (Suzune Toyama) to find her sister, Enka singer Sakura Tanizaki (Sayuri Taki), who has disappeared. What seems to be a simple missing person search soon turns into a case involving one of Osaka’s most influential yakuza gangs. Yoshida realizes that the leader of the Kosaka clan (Choshu Kagei) was also behind the murder of his girlfriend. Yoshida's only allies are his former mentor (Kan Mikami) and his two best friends, restaurant owner Tatsuo (Tatsuo Morizawa) and bartender Aya (Tsuyu). Against overwhelming odds, Yoshida fights alone in the water city of Osaka, and is drawn into more turmoil. Not unlike a sailor being lured by the sad voice of the Sirens.