A dead patriarch's fortune and strangely written will lead to scandalous family murders. And a brilliant detective uncovers a web of love and hatred, ultimately leading to a frightening truth... Sahei Inugami (played by Tatsuya Nakadai), once "Japan's pharmaceutical king," is the founder of the Inugami conglomerate. Sahei passes away, leaving a massive fortune and a large family. His complex lineage includes three daughters, each born of different mothers. The daughters are Matsuko (Junko Fuji), Takeko (Keiko Matsuzaka) and Umeko (Hisako Manda). Each daughter has a son: Sukekiyo (Kikunosuke Onoe), Suketake (Shingo Katsurayama) and Suketomo (Mansaku Ikeuchi). Living with the whole family in Sahei's mansion is the beautiful Tamayo Nonomiya (Nanako Matsushima). She is the granddaughter of a man who helped Sahei build his wealth, a man to whom Sahei owed all to... Wakabayashi, executer of the will, foresees the deadly conflicts between the family members and asks the detective Kosuke Kindaichi (Koji Ishizaka) for help. Before Kindaichi can meet him, Wakabayashi is killed. The will is read to the family. All are shocked. "Tamayo will inherit the entire fortune on condition that she marry one of my grandchildren: Sukekiyo, Suketake, or Suketomo." Sahei's demands start a bloody battle, pitting each relative against the other. As Wakabayashi feared, family members befall grizzly murders as everyone struggles for the fortune now resting with Tamayo. The detective Kosuke Kindaichi investigates the murders, finding deeply buried secrets behind the family's lineage. Ultimately, Kosuke discovers an unimaginable Inugami secret!