The team identifies the unsub as a "collector" with a deep-seated psychopathology, likely stemming from damage to the pre-frontal cortex that prevents her from distinguishing between living beings and objects.
The title refers to the psychological theory that human-like figures (like dolls or robots) become increasingly unsettling as they look more, but not perfectly, human. [S5E12] The Uncanny Valley
The Behavioral Analysis Unit (BAU) is called to Atlantic City after two women are found dead and posed in public places that represent childhood—a playground carousel and a swing set. The victims are physically well-cared for but have been kept in a drug-induced, conscious coma for months. The team identifies the unsub as a "collector"