The Snow Empress (2007)

Samurai detective Sano Ichiro and his wife trek to the remote Japanese island of Ezogashima in search of their son, who has been kidnapped by a political adversary. There, they find a region under siege by Lord Matsumae, driven mad by the murder of his mistress. Sano agrees to track down the mistress' killer in the hopes of restoring peace and recovering his son. Everyone is a suspect in The Snow Empress, Laura Joh Rowland's 12th Sano Ichiro mystery. The author packs her tale with memorable characters and plenty of intrigue — though not enough to make up for distracting amounts of exposition and an anti-climactic ending. B-