Assassination begins with the events of 1853 when "four black ships" anchored at Edo Bay, sparking civil unrest and the major political manoeuvring that saw the end of the Tokugawa Shogunate. At a time when assassination had become a disturbing political tool, Shinoda's film follows Hachiro Kiyokawa, an ambitious, masterless samurai whose allegiances drift dangerously between the Shogunate and the Emperor.
Alongside Tokyo's Sumida River is a ragpickers' settlement known as Ant Village. One night, a young Catholic girl, Satoko Kitahara, who has been baptized under the name of Maria, comes to offer her services. However, Ant Village is not just an ordinary vagrants' community but a fine autonomous organization, and as the municipal authorities have long been demanding that the people of Ant Village leave the site, Satoko is utilized to publicize the Village and win public sympathy. While being utilized in this manner, Satoko is nevertheless glad to be able to help the people of Ant Village, especially the children, and when the summer vacation comes she decides to take the children on an excursion to Hakone. To raise funds for this purpose she becomes a rag-picker herself.
