Detective Inspector Mark Olbeck and his partner have their day rudely interrupted when they witness a group of men attacking another in the street. Arrests are made but DI Kate Redman and the other officers of the Abbeyford police force are intrigued by their motive.

The dark side of vigilantism is revealed when a body is found, and the laptop of the victim reveals some true horror. But is this a simple case of a paedophile hunter's quest gone wrong? Or is there something more to this murder?

Who is the real victim here? Kate, already struggling with a life-changing decision, has to draw on all her experience, wisdom and courage as she and her colleagues hunt a ruthless killer...