Psychological profiler Tony Hill is trained to see patterns, to decode the mysteries of human behaviour, and when he comes across a series of suicides among women tormented by vicious online predators, he begins to wonder if there is more to these tragedies than meets the eye. Similar circumstances, different deaths. Could it be murder? But what kind of serial killer wants his crimes to stay hidden?

Former DCI Carol Jordan has her own demons to confront, but with lives at stake, Tony and Carol begin the hunt for the most dangerous and terrifying kind of killer - someone who has nothing to fear and nothing to lose . . .