Ichiyanagi Kenzou was supposed to have a bright future as a university scholar, but became ill and since then withdrew in the mansion of his family. Suddenly, at the age of 40, he decides to marry the 15 years younger Kubo Katsuko. She is a respectable young woman earning her own money as a girls school teacher, but the marriage is not exactly tolerated from the Ichiyanagis. Even though they still believe in standing and pedigree instead of thinking of the present and future, the ceremony takes place eventually. However at 4 in the morning screams and the shrill plucking of a koto rouse the family and their guests. When they look after the newly wed couple in their annex, they find them gruesomely slaughtered by a katana that is found stuck in the snow around the rear entrance. What is more, the sliding doors were locked from the inside and no footprints of the culprit were found that could hint at the culprit's escape... Kindaichi Kousuke, a detective that became renowned recently, is summoned to call this locked room murder.
