The Iris Fan by Laura Joh Rowland

The last four years have been disastrous for Sano Ichiro, a samuri in the 1709 court of his shogun, the ruler of Japan.  During this time, he has been demoted from the court's chief investigator of crimes to a lowly foot patrol soldier, as his enemies manage to foil his attempts to reveal their crimes.  Each time he fails to bring the truth forward, his livelihood is reduced again.  Even more wrenching, he sees the discord his stubborn insistence on the truth has brought to his family.  His wife, Reiko, formerly a partner in his investigations, is furious with him and the poverty he has brought to the family.  Their children are blocked from good jobs or advantageous marriages, and one false step can mean that the whole family will lose their lives.

Then an unimaginable crime occurs. Someone slips into the shogun's sleeping chamber and stabs him with a fan, a fan with razor-sharp folds.  Who could have done such a horrible crime?  There are two contenders for the shogun's position when he dies.  Yanagisawa and Lord Ienobu are rivals for the position, Ienobu for himself and Yanagiasawa for his son.  Unfortunately, both are Sano's enemies, as he has tried to bring their crimes over the years to light.  They form an uneasy alliance and are both displeased when Sano is brought back to the castle and restored as the Chief Investigator.  Can he solve the crime before the shogun dies?  If he doesn't find a way to reveal the assassin, one of his enemies will ascend to power and the first act will be revenge on Sano and his family.

Laura Joh Rowland has written a series of feudal Japan that has enthralled readers for many novels.  This is the eighteenth book in the series and the ending one.  The cruelty and constantly shifting alliances and betrayals that make up the court are stunning.  Everyone seems to be out for themselves, yet profess to follow the Bushido way of honor.  This book is recommended for both mystery readers and readers of historical fiction.