After being forcefully inducted as a soldier into war in 14th century Japan, his wife and mother remain living in a swamp. They eke out their living by ambushing worn-out warriors, killing them and selling their belongings to a greedy merchant. The woman comes to mistrust her daughter-in-law who has coupled up with a deserter, and begins to wear a facial mask she has taken from a slain samurai. Soon the mask will not come off again. In this disguise she is at first taken for a demon by her daughter.

Amorality in Japan. Tome is born into poverty in rural Japan, in the late 1910s. Chuji, her father, dotes on her; her mother is less faithful. Tome becomes a neighbor's mistress, works at his mill as World War II rages, and has a daughter. After an affair with a mill supervisor, Tome goes to Tokyo to seek her fortune. She leaves the child, Nobuko, in Chuji's care. Tome's a maid at a brothel, learns trade from the madam, enjoys the protection of a businessman whose mistress she becomes, and is soon herself the boss. As Chuji ages and Nobuko grows up with her own ideas, can Tome's self-preserving schemes provide continued comfort? Or will the mice scamper over her?