Inspector General Kanjuro Sano conspires with the future shogun twin brother. They replace Ieyoshi Tokugawa with his twin, but it becomes a problem when suspicion arises and Nemuri Kyoshiro gets involved.
眠狂四郎は、徳川家慶主従の刃に追われる娘志津を助けたことから、将軍世継ぎをめぐる渦中にまき込まれた。志津の言葉から、手掛りの糸を家慶の乳母で侍女頭の松浦に求めた...