When the only son of a working class woman is fatally struck by a car driven by the adulterous wife of a company president in a hit-and-run, the victim's mother changes her identity and infiltrates the couple's home to work as their maid, plotting to murder their similarly-aged son.

A cynical samurai is left as the sole survivor to fulfill a plot to assassinate the puppet of a villain intent on usurping the shogunate in the 17th century. A Shogunate Elder connives to rule Japan by making his puppet, the Shogun's brother Tsunashige, the next Shogun. The best strategist in Japan, Yamaga, leads a plot to stop the Elder, but his cabal is betrayed and most of the conspirators are captured and tortured.