The Crane Pavilion. Akitada Mysteries, #12

After the loss of his wife and newborn son, Akitada returns home, ostensibly to care for his motherless children, but really to withdraw from the world into his grief. When his friends and family join in an effort to draw him out of his seclusion by tempting him with a mystery, he responds halfheartedly until he becomes intrigued by the young woman's alleged suicide and the slipshod way in which the police investigated.  But more serious problems arise: he faces dismissal and punishment for having left his last post without permission.
Then Tora and Saburo are arrested for the murder of a gambler. Their dilemma forces Akitada to delve into the world of a gangster boss who controls gambling and prostitution, and this time Akitada will not escape.