Edie Ledwell, the co-creator of a cult TV cartoon, The Ink Black Heart, is being harassed by an online figure, Anomie. She asks Robin to uncover Anomie's true identity.

Robin, Strike and Barclay all take risks to further the investigation now that they think Anomie probably killed Edie Ledwell. Strike receives an unexpected and unwelcome visitor.

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.