Provincial lord of the Arioka Castle, Murashige Araki, rebels against tyrannical despot Oda Nobunaga, and makes a stand at his stronghold castle. He decides to take siege but is subsequently surrounded by Oda's forces, leaving its denizens isolated and in need of allies. With the sensitive support of his wife Chiyoho, Murashige struggles to keep his hot-blooded retainers in check, while also protecting the castle and its people. One day, a young samurai is murdered within the fortress with the mysterious killer unknown. A succession of bizarre incidents follows. The suspects are Murashige's close retainers and the people inside the Arioka Castle's land. Outside, enemy troops lie in wait. Inside, traitors lie to conceal themselves. As suspicion runs rampant, Murashige seeks the help of a prisoner in his dungeon—dangerous master tactician Kanbei Kuroda—to solve the mysteries.