It is a lost art, passed down by the ancients in great secrecy: Dim-mak. It is death, by the lightest touch of a finger. Sano Ichiro, tenuous in the new regime as the shogun's second-in-command, does not have the luxury of scepticism – another senior official is dead, a fingerprint lightly glazed into his skin.
Sano's wife Reiko has an investigation of her own: a beautiful, proud, and hopelessly poor woman has confessed to murdering her family. Yet the pieces do not fit, and as Reiko looks deeper into the woman's life as a hinin – a moral outcast, shunned by the world – inexplicable connections appear between her investigation and Sano's.
As Reiko's questions spiral her further into the squalor of life as a hinin, Sano and Hirata – his most loyal samurai – pursue their prey, uncovering an intricate tapestry of betrayal woven into the highest levels of the new regime. But they are no match for the one who has mastered dim-mak, a warrior who will strike all those who cross him or his path – even Reiko.