When the wealthy patriarch of the Inugami dynasty dies, he leaves his fortune to Tamayo (Yoko Shimada, Shogun), a young woman from outside the family. There is one condition: she must marry one of his grandsons. As the family gather in the stately mansion to discuss the situation, grisly murders occur. Detective Kosuke Kindaichi arrives to investigate the case and uncovers the secret history of the family's bloodline.