Japan, 1709. Amid the ever-treacherous intrigue in the court, Sano Ichiro has been demoted from chamberlain to a lowly patrol guard. His relationship with his wife Reiko is in tatters, and a bizarre new alliance between his two enemies Yanagisawa and Lord Ienobu has left him puzzled and wary. Then a harrowing, almost inconceivable crime takes place. In his own palace, the shogun is stabbed with a fan made of painted silk with sharp-pointed iron ribs. Sano is restored to the rank of chief investigator to find the culprit. This is the most significant, and most dangerous, investigation of his career. If the shogun's heir is displeased, he will have Sano and his family put to death without waiting for the shogun's permission.