Spike Falconer is in prison on the Isle of Wight - convicted of murder. What made him choose four innocent strangers, a family picnicking, as his victims? Why did he need to kill? Forensic psychologist Karen Taylor comes to probe the mind of this psychopath. Trying to recover from the death of her husband and the dark memories surrounding it, Karen is drawn into life on the Island. She becomes involved with DCI Charlie Trench, cool and abrasive, the opposite in every way from her partner Will Hawkins. And she has to get to know Spike's adoptive family, the rich and influential Falconers, who are tight-lipped and closing ranks. Someone on the Island doesn't want Karen getting too close to Spike. The more she learns, the more afraid she becomes of those who are threatened by her discoveries. And then they start to act ...