What starts as a routine missing-child report, when six-year-old Lucy Fielding gets lost near an old Sheffield mill, ends in the death of a young woman. Lucy tries to warn the people she cares about of the danger - she knows that there are monsters lurking in the deserted, rambling park, and she knows that they are getting closer - but no one is listening.

Suzanne Milner, Lucy's neighbour, is a potential witness to the crime. And she soon finds that her work as a researcher at a centre for young offenders is pulling her ever deeper into the web of intrigue surrounding the woman's murder.

For DI Steve McCarthy, the seemingly straightforward case takes a darker twist, leading him through a maze that involves drugs, lies, evasions and confrontations with the past. There are many questions thrown into his path, including the most puzzling: Why is Suzanne lying to him? But if he is to prevent an even greater tragedy, he must find some answers, and time is running out.