The novel tells the tales of four women, working the graveyard shift at a Japanese bento factory. All four women live hard lives. Masako, accepted as the leader of the four women, feels completely alienated from her estranged husband and teenage son. Kuniko, a plump and rather vain girl, has recently been ditched by her boyfriend after the couple were driven into debt leaving Kuniko to fend off a loan shark. Yoshie is a single mother and reluctant caretaker of her mother-in-law, who was left partly paralyzed after a stroke. Yayoi is a thirty-four-year old mother of two small boys. She hates to leave her children home alone to go to work. More than that, she hates the thought of her drunken, gambling husband returning home and hurting them or, more likely, herself.
Returning home one night, Yayoi discovers her husband has gambled away all their savings and loses control of her temper. She strangles him to death.
She desperately persuades Masako, who eventually gets Yoshie and Kuniko involved, to help her dispose of the body.