'She lifted the flap of the envelope and pulled out the single white page. As she opened it up she stared, open mouthed. Four words were typed on the page. I am watching you.'When Amy Whyte and Penny Brogan leave a local nightclub in the early hours of Sunday morning and don't arrive home, their families are beside themselves with worry. Conor Dowling has just been released from prison, a man full of hatred for Amy, the girl who put him behind bars in the first place.The case is given to Detective Lottie Parker, when the girls' blood-soaked bodies are found, days later, in a derelict squat. Chillingly, both girls are clutching silver coins in their hands - what message is this killer leaving behind? All the signs point to Conor but his alibi is water tight.As Lottie examines Penny and Amy's final days alive in a desperate search for clues, two more girls are found stabbed to death in a luxury apartment complex. Caught up in what is fast becoming her toughest case yet, Lottie is unaware that somebody is watching her every move.Then Lottie's two daughters, Katie and Chloe suddenly disappear from the town centre. Terrified that the killer has her girls, the stakes have never been higher for Lottie. But as Lottie puts everything on the line to find her daughters and solve the case, she's about to find herself in terrible danger - someone has a personal axe to grind with her and they know the best way to get to her is to hurt the ones she loves the most.