Over the course of the searches, Hyong-chol remembers how Mom pushed him to do well on his exams, how disappointed she was when he failed the entrance exam to university, how she continued to make sacrifices for him, and ultimately, how badly he treated her. As Hyong-chol and Chi-hon follow every possible lead as they try to track Mom down, they discover that she is following something of a pattern, visiting every place where Hyong-chol lived, or worked, or both. The novel's second section, 'I'm Sorry, Hyong-chol' is narrated from the third-person perspective of Hyong-chol himself who wonders what he was doing at the moment Mom disappeared, worries about how to find her, and begins to feel guilty about not being a better son.

The narrator also contemplates the narrator's relationships with Mom and also with the narrator's younger brother, the over-achieving and much resented Hyong-Chol, to whom Mom devoted much of her time and energy. Her narration describes the family's attempts at finding Mom who got separated from her husband, Father, while they were hurrying through Seoul's busy train station, contemplating the various unusual circumstances that might have brought Mom and Father to the station at that particular time.

The first part of the story, 'Nobody Knows,', is written from the first-person perspective of Mom's eldest daughter, whose name is not revealed until the novel's second section. This novel, translated into English from the original Korean, explores how individual members of a family are traumatized by the sudden and unexplained disappearance of 'Mom.' As the narrative explores the loss, self-recrimination, and in some cases, self-discovery experienced in the aftermath of Mom's disappearance, it also considers themes related to the self-sacrifice of mothers, the relationship between past and present, and the shifting nature of identity.

Please look after my mother