(English title: The Only Child ) is a psychological thriller by South Korean author Seo Mi-ae . It centers on Seonkyeong , a criminal psychologist and university lecturer who finds herself simultaneously investigating a notorious serial killer and managing her increasingly disturbing 11-year-old stepdaughter, Hayeong . Core Narrative & Parallel Plotlines
: Both the killer and the child use manipulation to unsettle Seonkyeong, with the killer even offering her "advice" on how to handle the girl. Characters
The novel intertwines two primary story arcs that Seonkyeong must navigate:
The book is frequently described as a blend of The Silence of the Lambs and The Bad Seed .
: The narrative explores how hidden family secrets and past abuse can manifest in the next generation.