Edo, September 1693. Fire destroys the Black Lotus Temple, leaving three bodies and an orphaned girl named Haru apparently responsible for the disaster. Sano discovers that the victims were murdered before the building burned, turning a religious tragedy into a triple homicide.
Reiko believes Haru is innocent and enters the temple community against Sano’s wishes. Her inquiry exposes extortion, sexual exploitation and secret rituals behind the institution’s public charity. As husband and wife adopt opposing theories, the case threatens both their marriage and their survival inside a sect prepared to defend its authority.