Teenager Nikki Bell is the only witness to the brutal murder of two members of her family and their cleaner. She's lucky to be alive. But the murder isn't a one-off. It's part of a bigger, more violent attack planned on affluent families in the area - and now Nikki, as the only living witness, is a dangerous threat to the well-orchestrated scheme. As the net draws tighter around the killers, DI Rio Wray must do whatever it takes to keep Nikki alive. But when you're dealing with criminals, there's no line they won't cross... In a kill-or-be-killed-world, who will be first to pull the trigger?