Samon Kamiyama, a skilled yoriki under Toyama Saemon-no-jō Kagemoto is feared and known to the villains as “Samon from the Hell.” Samon suspects that the drowning incident at the raw silk wholesaler Shinano-ya was the work of Maruya Rihei, a kimono wholesaler favored by the Ōoku, but has no evidence to prove his allegation. The elder Arao Tsushima-no-kami who is colluding with Maruya plan on building a gold mine on an uninhabited island using prisoners. Arao gives the supervision charge to Samon, who along with his comrades and Horikawa takes up his post on the island but is attacked by assassins one after another.