Amid the political machinations of feudal Japan, Sano faces a daunting, complex investigation.

Twenty months spent as the shogun's most honourable investigator of events, situations and people have left Sano weary. He looks forward to the comforts of his arranged marriage and month's holiday to celebrate the union with his new wife. However, the death of the shogun's favourite concubine interrupts the couple's wedding ceremony as Sano is recalled to perform his duty.

After Sano traces the cause of Lady Harume's death to a self-inflicted tattoo, his must travel into the cloistered world of the shogun's women to untangle the complicated web of Harume's lovers, rivals and troubled past, and identify her killer.