This black and white film is set in November 1839, during the final decades of
Japan's
Tokugawa shogunate. The retired
Shōgun's youngest son, Lord Nariatsu, crosses into the neighboring Oshi fief while he's hunting. Confronted by the Clan Lord Abe Masayori for just killing one of his vassals, Nariatsu kills him in a fit of pique. The Oshi fief retainers appeal to the Shōgun's Council of Elders for justice. Not wishing to embarrass the Shōgun's Tokugawa Clan, Chief Secretary Mizumo rewrites the event. He places Clan Lord Abe in the wrong and Lord Nariatsu defending himself. For this "attack," the Oshi fief is to be abolished at the end of the month, and the income from the lands given to Lord Nariatsu as compensation. Angered by this gross injustice, Chief Retainer (Chamberlain) Tatewaki approaches childhood friend, Sengoku Hayato, and asks him to avenge their Lord's murder. Hayato agrees to assemble a small band of loyal
samurai. Hayato and nine Oshi fief samurai vow to trade their lives for justice. They follow Nariatsu to
Edo (feudal Tokyo) where they are joined by Ido Daijuro, a
rōnin (wandering samurai) with a thirst for revenge against lords after tragic injustice to his family. Hayato and his ten followers plan to ambush Nariatsu with his large escort as he travels from the brothels of Edo to the safety of his castle in the Tatebayashi fief. As they are about to attack, Hayato receives a letter from Tatewaki ordering him not to kill Nariatsu, because Councilor Mizumo has told him that the council is likely to reverse the decision to abolish the Oshi fief. While some samurai initially refuse to obey, Hayato enforces the order because obedience is a samurai's first duty. Later, Daijuro tells the others that Hayato has more reason to disobey than they do. His wife, Lady Orie, has already committed
jigai in anticipation of Nariatsu's death and the retired Shōgun's wrath. When Tatewaki discovers that Councilor Mizumo lied, he rides to Hayato and orders him to kill Nariatsu. Ashamed that he was duped, Tatewaki commits
seppuku. The eleven samurai establich a stonghold in a small village to catch Nariatsu and his bodyguards in the town at the river crossing to his fief, where Nariatsu has tarried due to a rainstorm. In a great battle against the 50 elite bodyguards, Hayato eventually hunts down kills Nariatsu. Afterwards, few except Hayato and Gyobu are still standing. Gyobu corners Hayato and attacks only to find that Hayato, although holding his sword, makes no defense against Gyobu's mortal sword thrust. Gyobu asks Hayato why he did not parry his deadly thrust and Hayato tells him that this is how it must be before dying. Hayato had decided that after completing his mission of vengeance, that he would then have to sacrifice his own life in fulfillment of his sense of honor as a samurai. Daijuro appears—he has dispatched the last of the bodyguards. Daijuro cuts off the already dead Nariatsu's head and walks away, happy in his vengeance. When the rumors of the kataki-uchi (vendetta) spread, the Oshi fief is restored to the Abe clan. And, the council of elders releases a statement that the retired Shōgun's youngest son has died of an illness. ==Cast==