Yasuko Hanaoka works in a restaurant. She is divorced, and is a single mother to Misato. Her ex-husband, Togashi, was an abusive man, stalking and extorting money from her. With similar intentions, he showed up at Yasuko’s home, this time threatening to kill her and her daughter if she refused to lend him money. What started from denial, reached to a heated argument, and within a short span of time, turned to a nasty fight. In the spur of the moment, Yasuko killed Togashi. Hearing the commotion in their apartment, Tetsuya Ishigami came into the picture. Ishigami was a middle-aged, single math teacher, who evidently had a growing affection for Yasuko. He offered not only to help her dispose of the corpse, but also to devise a logical plan to cover up the entire incident.

Later, the body was recovered from where it was disposed of. The principal investigator, Kusanagi, was certain of Yasuko’s involvement with the murder but was unable to find sufficient evidence. For a better insight, he summoned the assistance of the ingenious physicist, Dr Manabu Yukawa. Yukawa was a schoolfriend of Ishigami, and he suspected Ishigami. As the story progresses, there are more interesting twists and turns, keeping the readers thrilled and speculating.