When a tycoon passes away, he unexpectedly leaves the family fortune to outsider Tamayo on the condition that she marries one of the grandsons, pitting blood against blood.

Kôsuke Kindaichi, a somewhat peculiar private detective, visits a remote town. He meets a police detective and they start to investigate an old unsolved murder. Then some murders happen. Kindaichi must find out about the past in order to reveal who the murderer is.

A scruffy detective investigates the murders of three sisters on a small Japanese island in 1946.

To solve the mystery of a murder of an old governess which takes place at a wealthy Daidoji family's country estate, family secrets and lies dating back several generations must be sorted out once and for all.

This time, Kousuke investigates a murder in a hospital. The murderer leaves misleading evidence to divert Kousuke's attention on the case. Suspicion and doubt clouds Kousuke's mind.

Inugami Sahei, who built up the wealth of the Inugami Clan, passes away, leaving a will with Furudate, his legal adviser, for his daughters Matsuko, Takeko and Umeko, all of whom have different mothers, and for their sons, as well as for Nonomiya Tamayo, the granddaughter of a person to whom Sahei feels heavily indebted. The will states that all his assets are inherited by Tamayo alone, on the condition that she marries one of the sons of the daughters. Furudate's assistant learns the content of the will, and seeks advice from Kindaichi Kosuke, a private detective, as he senses the air of unease. Shortly afterwards, murders start to occur one after another in the clan.

When a woman and her bridegroom are found dead in a double suicide the day after their wedding, it is up to the detective to figure out what could possibly have motivated them. Carefully and systematically, he pieces together the inner lives of the two.