It’s 2am in Glasgow and DI Rachel Narey is ready to give the signal to break down the door of a violent rapist. At her word, officers charge into the south-side flat.They find the man cowering in a corner of his bedroom, pleading not to be arrested, begging to be left alone. Narey reads him his rights and produces the warrant to search the property. Suddenly than man, Robert Broome, launches himself at her, turning from prey to predator in an instant. While cops restrain him, others begin the search of his flat.
 
In a hidden recess under the carpet they find photographs. Hundreds of them. All of women, most taken without the subject being aware. On the street, in playgrounds, in shopping centres, some simply printed copies of Facebook images. Narey studies them, seeing the same faces repeated over and over again. She knows they have stumbled over a repeat offender and the scale of what he might have done terrifies her.
 
But even with Broome in custody, these women are still, somehow, being hunted and killed. The clock is ticking, the police are way behind and the stakes have just got higher.