During the tumultuous end of the Tokugawa shogunate, the Tengu Party rose in rebellion in Mito. Friends from their hometown, Tanaka Genzo and Fujita Koshiro, each walked different paths. Koshiro, who upheld the philosophy of "Revere the Emperor, Expel the Barbarians," became a leader of the Tengu Party, taking refuge in the mountains. Genzo, however, did not have any particular ideological stance.

In the town of Izu known for its hot springs, Den Shichi from Kuromon Town sets off for a healing trip with his companion, a bamboo craftsman with a nose like a lion's snout, at a time when the town is under a tight security network due to a nearby gunpowder depot explosion. Staying at Tsuruya, Den Shichi and his group are investigated by officials whose behavior seems somewhat odd. That night, a man looking like a craftsman is murdered, and gunpowder residue is found at the scene, prompting Den Shichi to suspect that something is amiss.

A samurai detective film.

A swordsman must foil a minister's sinister plan to assassinate the shogun.