Edie Ledwell, the creator of a popular cartoon, is being harassed by a shadowy online figure known as "Anomie." She appeals to Robin to uncover her tormentor's identity.
Robin and Strike make a major breakthrough, having eliminated several suspects. Robin's cover is blown, and Strike stays the night at her new flat. Meanwhile, Anomie claims another two victims.
The agency is the target of a devastating attack. Strike figures out who killed Edie, and having secured proof, Robin puts herself in danger in order to save lives.